AFML-TR-65-192A o t q6•-7 § y b#OFIZICIAL

SYNTHESIS OF GROUP IV ORGANOMETALLICPOLYMERS AND RELATED COMPOUNDS

A. I. LEUSINK1. G. NOLTES

H. A. BUDDINGG. 1. M. VAN DER KERK

INSTITUTE FOR ORGANIC CHEMISTRY, T.N.O.UTRECHT, THE NETHERLANDS

TECHNICAL REPORT AFML-TR-65-192

DECEMBER 1965

AIR ,%ý\&'AT LS LABORATORYRESEA' WAND TECHNOLOGY DIVISION

AIR FORCE SYSTEMS COMMANDWRIGHT-PATTERSON AIR FORCE BASE, OHIO

Distribution of this document is unlimited.

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Copies of this report should not be returned to the Research and Tech-nology Division unless return is required by security considerations,contractual obligations, or notice on a specific document.

400 - February 1966 - 773-31-619

AFML-TR-65-192

SYNTHESIS OF GROUP IV ORGANOMETALLICPOLYMERS AND RELATED COMPOUNDS

A. 1. LEUSINK1. G. NOLTES

H. A. BUDDINGG. 1. M. VAN DER KERK

INSTITUTE FOR ORGANIC CHEMISTRY, T.N.O.UTRECHT, THE NETHERLANDS

Distribution of this document is unlimited.

AFML-TR-65-192

FOREWORD

This work was prepared by the Institute for Organic Chemistry, T.N.O., Utrecht, theNetherlands, under USAF Contract No. AF 61(052)-218. The contract was initiated underProject No. 7023, Task No. 73666, and was continued under Project No. 7342, "Funda-mental Research on Macromolecular Materials and Lubrication," Task No. 734203,"Fundamental Principles Determining the Behavior of Macromolecules." The work wasadministered under the direction of the European Office of Aerospace Research, UnitedStates Air Force, Brussels, Belgium.

This report covers work conducted from I March 1959 to 29 February 1964. The manu-script was released in June 1965 by the authors for publication as an RTD technical report.

The work was carried out under the supervision of Prof. G. J. M. Van der Kerk, Di-rector of the Institute for Organic Chemistry T.N.O., Utrecht, the Netherlands.

This technical report has been reviewed and is approved.

WILLIAM E. GIBBS,Chief, Polymer BranchNonmetallic Materials DivisionAir Force Materials Laboratory

ii

AFML-TR-65-192

ABSTRACT

The synthesis and characterization have been described of linear polymers, having a carbonchain regularly interrupted by the Group IV elements silicon, germanium, tin, or lead. Suchpolymers have been obtained by means of:

a) Poly-addition reactions involving an organotin dihydride and either a dienic, a diynic, ora monoynic compound.

b) Wurtz-type poly-condensations involving appropriate combinations of p-chlorophyenyland chloro derivatives of the Group IV elements.

The synthesis and polymerization of vinyl-type Group IV organometallic monomers isdealt with briefly.

Furthermore, interesting Group IV metal-containing heterocycles have been preparedand also a few polymers containing, in addition to Group IV atoms, other hetero-elementsin their backbone.

All polymer-forming reactions have been studied by carrying out model reactions on alow-molecular weight level.

iii

AFML-TR-65-192

TABLE OF CONTENTS

SECTION PAGE

ADDITION REACTIONS INVOLVING ORGANOTIN HYDRIDES ANDUNSATURATED COMPOUNDS ............................. 1

A. Discussion ....................................... 1

B. Synthesis of Low-Molecular and Polymeric Adducts fromOrganotin Hydrides and Olefinic Compunds ................. 3

C. Synthesis of Cyclic Monomers and Linear Polymers fromOrganotin Hydrides and Acetylenic Compounds ............... 10

D. Synthesis of Low-Molecular and Polymeric Adducts fromOrganotin Hydrides and Vinyl Derivatives of Group IVMetals Containing the p-Phenylene Group .................. 15

E. Synthesis of Low-Molecular and Polymeric Adducts fromp-Phenylene-Bis(Dimethyltin Hydride) and Olefinic andAicetylenic Compounds ............................... 17

F. Synthesis of Polymers from Organotin Dihydrides andUnsaturated Esters and Amides ......................... 21

II PREPARATION AND POLYMERIZATION OF GROUP IV ORGANO-METALLIC DERIVATIVES OF STYRENE, a -METHYLSTYRENE,ISOPRENE, AND ACRYLIC ESTERS ......................... 27

A. Discussion ....................................... 27

B. Synthesis of Group IV Organometallic Derivatives ofStyrene and a-Methylstyrene .......................... 27

C. Homopolymerization of Group IV OrganometallicDerivatives of Styrene and Q-Methylstyrene ................ 28

D. Synthesis and Attempted Polymerization of Group IVOrganometallic Derivatives of Isoprene and Acrylic Esters ...... 32

IlI BIS-CYCLOPENTADIENYLTITANOXANE DERIVATIVES OF GROUPIV METALS .. ....................................... 37

A. Discussion ....... .................................... 37

B. Synthesis of Triphenylsiloxy Derivatives of Bis-Cyclopenta-dienyltitanium ...... .................. .... ............ 37

C. Attempted Synthesis of Bis-CyclopentadienyltitanoxanePolymers of Group IV Metals ................................. 38

IV WURTZ-TYPE CONDENSATIONS LEADING TO GROUP IV ORGANO-METALLIC OLIGOMERS AND POLYMERS CONTAINING THE p-PHENYLENE GROUP .........-- o........... 41

v

AFML-TR-65-192

TABLE OF CONTENTS (Continued)

SECTION PAGE

A. Discussion ....................................... 41

B. Synthesis of Oligomeric and Polymeric p-Phenylenesilanes ...... 41

C. Synthesis of Oligomeric and Polymeric p-Phenylenegermanes ..... 48

D. Attempted Synthesis of Oligomeric and Polymeric p-Phenylenestannaness ................................. 49

E. Investigation of Other Condensing Agents ................... 52

V SYNTHESIS AND DEGRADATION OF GROUP IV ORGANO-METALLIC DERIVATIVES OF ORGANIC SALTS ................. 55

A. Discussion ....................................... 55

B. Synthesis and Attempted "Decarboxylation" of Group IVOrganometallic Cyanoacetates, Benzoates, Thiobenzoates,and Dithiobenzoates ................................. 56

C. Synthesis and Desulphination of Organotin Sulphinates .............. 57

VI AN APPROACH TO THE SYNTHESIS OF A QUASI-AROMATIC SILA-AND STANNATROPYLIUM ION ............................ 61

A. Discussion ....................................... 61

B. Attempted Syntheses of Group IV Metal-Containing Hetero-cycles via the Wittig Reaction or via Condensation Reactionswith o,o'l-Terphenylenedilithium ........................ 63

C. Synthesis of Linear and Cyclic Tin-Containing Compounds byMeans of Organotin Hydride Addition Reactions ............... 65

D. Degradation of Stannacycloheptatriene Derivatives by Iodine ....... 70

VII INFRARED SPECTROSCOPY OF GROUP IV ORGANOMETALLICCOMPOUNDS IN THE ROCKSALT REGION .................... 75

VIII SUMMARY AND CONCLUSIONS ............................ 79

IX REFERENCES ....................................... 89

vi

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TABLES

The preparation and characterization have been reported of various low-molecular andpolymeric compounds, the majority of which have not been described before. Essentialdata of about two hundred compounds (successively numbered from 1 through 207) arepresented in the tables listed below. The compounds, the number of which has been markedwith an asterisk, are compiled in Table 25.

TABLE PAGE

1. Addition Products from p-Styrenyl-Substituted Group IV Metal Derivativesand Organotin Hydrides ................................... ..... 5

2. Polymers from Dienic Compounds and Organotin Dihydrides ............. 6

3. Polymers from Di-p-Styrenyl-Substituted Group IV Metal Derivativesand Organotin Dihyirides .................................. 7

4. Thermogravimetric Analysis of Some Group IV Metal Poly-AdditionPolym ers ............................................. 9

5. 1-Stanna- and 1-Germa-2,6-Cycloheptadiene Derivatives ............... 13

6. Polymers from Diynic Compounds and Organotin or GermaniumDihydrides ............................................ 14

7. Polymers from Phenylacetylene and Organotin Dihydrides .............. 16

8. Divinyl Derivatives of Group IV Metals Containing the p-PhenyleneGroup . .............................................. 18

9. Addition Products from Divinyl Organometallics Containing thep-Phenylene Group and Triphenyltin Hydride ........................ 18

10. Addition Products from p-Styrenyl-Substituted Group IV MetalDerivatives and p-Phen3lene-Bis(Dimethyltin Hydride) ................ 20

11. Polymers from Unsaturated Compounds and p-Phenylene-Bis(Dimethyltin Hydride) ................................... 23

12. Ester or Amide Group Containing Organotin Dihydride AdditionPolymerss ............................................ 25

13. Triphenylmono- and Diphenyldi-p-Styrenyl Derivatives ofGermanium, Tin, and Lead ....................... ........ ...... 29

14. Trimethyl-p-Styrenyl and Trimethyl-p- a -Methylstyrenyl Derivativesof Group ITFElements .................... ............ 30

15. Thermal Degradation of Group IV Organometallic Polystyrenes ........ 33

16. Esters of 0-Trialkylstannylacrylic Acid from Propiolic Esters andTrialkyltin Hydrides ...................................... 35

vii

AFML-TR-65-192

TABLES (Continued)

TABLE PAGE

17. Some Oligomeric p-Phenylenesilanes Obtained by Wurtz-TypeCondensations ............................................ 43

18. Some Poly-p-Phenylenesilanes Obtained by Wurtz-TypeCondensati s..s .......................................... 44

19. Weight-Loss of Poly-p-Phenylenesilanes upon Heating at GraduallyIncreasing Temperaturee ................................... 46

20. Some Oligomeric and Polymeric p-Phenylenegermanes Obtained byWurtz-Type Condensations . ................................. 50

21. Decomposition of Triphenyltin Benzenesulphinate by Heating at~255°C .............................................. 59

22. Addition Products Obtained from Organotin Hydrides and o-Divinyl-o-Diethynylbenzene ...................................... 67

23. The Reaction of 3,3-Diethyl-3-Benzostannepin with Iodine in Benzene ..... 72

24. Some Infrared Absorption Characteristics of Group IV Organo-metallic Compounds ...................................... 76

25. Miscellaneous Compounds .................................. 82

viii

AFML-TR-65-192

SECTION I

ADDITION REACTIONS INVOLVING ORGANOTIN HYDRIDES

AND UNSATURATED COMPOUNDS

A. Discussion

In the years 1955-1958 at our Institute much attention had been paid to the information oftin-carbon bonds by the reaction of organotin hydrides with carbon-carbon unsaturatedcompounds (References 32-35). When our organometallic polymer program was initiatedit was decided to apply this reaction principle to the synthesis of organotin polymers. Aspectsof the chemistry of organotin hydrides related to the possibility of preparing polymers havebeen discussed before (References 20, 30, 31). Some points will be recalled briefly as thiswill lead to a better appreciation of the scope of the polymer-forming reaction.

Adducts are formed upon reaction of triorganotin monohydrides with a variety of mono-substituted terminal olefins (References 33, 34):

R3SnH + CH2 = CH-R' - R3 SnCH2 CH 2 R (I)

Reactions involving triphenyltin hydride proceed smoothly at moderate temperatures(70°-100°). Both the reaction time (usually a few hours, sometimes as short as a few min-utes) and the yield (generally high, in some cases quantitative) depend on the substituent R'.Trialkyltin hydrides react slower and only if the olefinic bond is activated sufficiently by R'(e.g., when R' represents an aryl group).

Where investigated (e.g., n-octene, acrylonitrile, styrene) the organotin group was foundto have added to the terminal olefinic carbon atom. Although polar effects influence the rateof the reaction, steric factors mainly determine its course. Terminal addition seems to bethe rule.

After the completion of the greater part of this work catalysts for the addition of organotinhydrides to unreactive olefins have been reported (References 36-39). Addition of the less-reactive trialkyltin hydrides to nonactivated double bonds has been realized using catalyticamounts of free radical producing compounds (References 36, 37) or organo-aluminium(References 37, 38). However, the simultaneous occurrence of side-reactions (References14, 37) may restrict the applicability of the free radical catalysis for polymer formation(compare also Reference 39). Catalysis by alkylaluminium compounds, which have beenfound to be inactive in addition reactions of the analogous trialkylsilicon and germaniumhydrides (Reference 15; compare also Reference 40), has not been investigated thoroughly yet.

Similar reactions have been realized using acetylenic derivatives as the unsaturatedpartner (Reference 34):

R SnH + HC--C-R' R3 SnCH-CHR' R3SnH R3 SnCH2 CHR' SnR 3 (II)

However, the reactivity of organotin hydrides towards carbon-carbon triple bonds is muchhigher than towards olefinic double bonds. Mostly, these reactions proceed exothermally inthe absence of any added catalyst. Consequently, when applying one mole of a monohydrideper mole of a monoacetylenic compound, only the olefinic adduct is being formed. Similarly,when applying two moles of a monohydride, two separate reaction steps can be distinguished,the second one requiring more severe conditions.

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AFML-TR-65-192

Considering the foregoing, the possibility of applying this reaction principle to the synthesis- of polymers is evident. Upon reaction of an organotin dihydride with an appropriate diolefine

(preferably an a , w -diene) linear polymers are being formed under incorporation of organo-tin groups in the main chain:

R

R SnH + CH 2 CHR' CH-CH2 -nCH 2CH 2 R (C I CH 1i)

R - n

Starting from acetylenic compounds as the unsaturated reaction partner, and making useof the earlier mentioned marked difference in reactivity of the organotin hydride towardsdouble and triple bonds, two different routes leading to polymers can be followed:

1. Reaction of an a ,o-diyne with an organotin dihydride in a 1:1 ratio under verymild conditions will result in the formation of a linear polymer. In this case thereaction ends after conversion of the triple bonds into double bonds:

R2 SnH2 + HC--CR C--CH [SnCH=CHR'CH=CH- (IV)

2. Reaction of a monoacetylenic compound with an organotin dihydride again in anexactly 1:1 ratio will proceed in two steps, viz. formation of an olefinic organo-tin monohydride and subsequently, at higher temperature, homopoly-addition ofthis monomer:

R R R'

R2 SnH2 + HC=CR' -- HSnCH-CHR' -SnCH 2 CH WV)

RR n

However, two molecules of the 1:1 addition intermediate may form a six-membered cyclicdimer with the two tin atoms in 1,4-position. This reaction course has in fact been observedupon reaction of diphenyltin dihydride with phenylacetylene (Reference 41). As noted from an

absorption peak at 988 cm- 1, originating from the C-H bending vibration of trans-disubstitutedethylene groups, the olefinic intermediate has the trans-structure, its formation presumablybeing promoted by steric factors (see also Section VI-C). The trans-structure, in its turn,favors the formation of the distannacyclohexane system:

Ph Ph

sCH CH -CH

P SnPh2 - Ph 2Sn SnPh2 (VI)

CH CH CH- CHPh Ph

2

AFML-TR-65-192

Dienic or diynic compounds having the two unsaturated groups in a sterically favorableposition have also been found to yield cyclic oligomers in addition to linear polymers. Re-action of diphenyltin dihydride with divinyl organometallic derivatives yields the bimetalliccyclohexane analogues (cyclic monomers) as the main product (Reference 41):

H2C-CH / CHi- CH I

Ph2SnH2 + MIV Ph PhSn MIph2 (VII)

H C=CH CH2- CH2 2 2

MIV =Si and Ge

Reaction of organotin dihydrides with 1,5-hexadiyne in addition to the expected polymersyields 1-stanna-2,6-cycloheptadiene derivatives (see Section I-C).

B. Synthesis of Low-Molecular and Polymeric Adducts from Organotin Hydridesand Olefinic Compounds

Considering the foregoing it would seem that the presence of voluminous aryl groups inthe dienic reactants, to be used in poly-addition reactions with organotin dihydrides, willsterically disfavor ring-formation and at the same time will activate the double bonds. Forthis reason 1,4-divinylbenzene (1*), 3,9-divinylspirobi(meta-dioxan), p,p'-diisopropenyl-biphenyl (2*) and the diphenyldi-p-styrenyl derivatives of germanium7 -tin, and lead (seealso Section HI-B) were selected as'dienic components.

Optimal conditions for polymer-formation have been determined by carrying out modelreactions of the mono-p-styrenyl derivatives of germanium, tin, and lead both with tri-phenyltin hydride and di~henyltin dihydride, as well as of the di-p-styrenyl derivatives withtriphenyltin hydride:

IV IVPh 3 SnH + H 2 CCH _0& 1WIPh 3 ~Ph 3 SnCH 2 CH 27 QMIPh3 (VII1I)

3-5, MIV = Ge, Sn, and Pb resp.

Ph 2 SnH 2 + 2 H 2C H GVPh 3 Ph 2 Sn( CH 2 CH .Q.M IV Ph 3 )2

(IX)IV

6-8, M Ge, Sn, and Pb resp.

2 Ph 3 SnH + (H2C=CH-0Q ) 2 MIVPh 2 2

(Ph 3SnCH2 CH 2 )2 M IVPh2 X)

9-11, MIV = Ge, Sn,and Pb resp.

3

AFML-TR-65-192

From each type of reaction the expected addition products were obtained in good yields.The compounds obtained in these reactions are listed in Table 1.

It thus appears, that contrary to vinyl and allyl groups, which are reductively cleavedfrom lead by phenyltin hydrides (Reference 42), the p-styrenyl group remains unaffected.Abnormal products which previously had been found to-result from reactions involving vinylor allyl derivatives (Reference 42), e.g.,

2 Ph3 MIVCH=CH2 + Ph 2 SnH 2 - Ph3MIVcH2 CH2 SnPh3 (XI)

have not been isolated.

The polymer-forming reactions of 1,4-divinylbenzene, 3,9-divinylspirobi(meta-dioxan) andthe diphenyldi-_•styrenyl derivatives of germanium, tin, and lead with diphenyltin dihydride(1:1 molar ratio) yielded glas slike products, which according to analytical results and solubilityproperties, are indeed strictly poly-addition polymers. Obviously the occurrence of vinyl-typepolymerization may be excluded: I"

R2 SnH2 + H2 C=C(R' )-R"-C( R' ) CH 2 - - -Sn-CH2-CH-R-CH-CH2 (X1I)

I ." I ILR R' R" n

16 -241 R " = IV

PhIP

The polymers derived from alkyltin dihydrides seem to be more or less crosslinked,judging from their solubility behavior. The. mechanism responsible for crosslinking is notwell understood. It is conceivable, however, that owing to the somewhat smaller reactivityof dialkyltin dihydrides as compared with diphenyltin dihydrides towards double bonds bothvinyl-type polymerization and occasional decomposition of Sn-H groups with formation of Sn-Sn groups leads to the occurrrence of branched structures.

The polymers obtained in reaction (XI1) are presented in Table 2 and Table 3.

The reaction of cyclopentadiene with organotin dihydrides did not yield the expected products.As noted from model reactions the reactivity of the remaining double bond in the monoaddi-tion product (25*) from triphenyltin hydride and cyclopentadiene is insufficient for uncatalyzedaddition:

•i• + Ph3 SnH

+ Ph 3 SnH - l SnPh no odduct (XIII)

Most probably 1,4-addition occurs in the formation of the 1:1 adduct (compare also Ref-erence 43).

4

AFML-TR-65-192

u) c O C; C; C; C; C; CO C

"Jr toa al a a a4aCDL 00 t- to CO O CD 00 wo C

-4 -l 14 t -

Io I

-tl (n VD 0)V Va 0 e. - 0 oo I- 1w 00 02 cC)

N "i rI rI Iq r- rI

C- 0 C)000 0-F4

;4 "oo 03mr q cq c

O4 0uO O LO C

V A -IJ

U,,

00 OD O) ILO C) to -ý

-44

V) Ve r Y e Y

co CO CO C q e q CO CO CD

0 u 0 1U U 0 U U 0 00 C0

0q eq eq4_ 4 eq eq P4 p P4 co e

Cod

0Y 0 O to 0 0 m 0> 0-02I r-

5C

A FML-TR-65-192

U.J r-4

ocý 00C

C:, CCD

-J c

0 0

IJ - 00. Ea w

04 00

0 CD q 00 c

*o tocoU- r- C1 q cq

0

C)d

0) 0

_ c.Lo1-4 C*0

~* ~ - d

0 - _ _ _ _ _ _ _ _ _ _ 6

AFML-TR-65-192

V5 C; V5 0; CO - C;

LL*CO CD - CIt- C CDt CO CDtIA. a - 00 a aIcaCea a

_ LIJLCOw1 10 0 cq tLCO

Cto000

uJ U C

ro (a)I CDC.

O i COC=OC-,: CD -4

= = P4)

C=Oro o

PQ k k kO Jq CD. C, 0o

(D D a)CD0 ro> to I0 to 00 C)

ce) ,e) 0o m

-. 4 CD t,0 0 t

kq eq eq eq( D 0kD0 C

CO C O CO COC

(D CD 0

Co e

CO q 0q P4 CO CO CO C P., C

oo L- 0 nr4 c ls-1 T-4 9 c .. 9 .

I:7

AFML-TR-65-192

Molecular weights of the polymers, determined by means of ultra-centrifuge measurements*according to Archibald (Reference 44) or osmometrically** are presented in Tables 2 and 3.It appears from these data that the attainment of appreciable molecular weights is possible.Interfering reactions, such as the thermal breakdown of the rather unstable Sn-H bond ap-parently do not occur under the reaction conditions used. A broad molecular weight distri-bution may be expected for this type of polymer-forming reaction(hydrogen transfer poly-merization). This is confirmed by the large differences between M and M observed (Memphasizes the high, Mn the low values). n w

In general, polymer-melt temperatures are quite low. Interchain forces will be ratherweak, because of lack of hydrogen bonding. Moreover, the relatively large metal atoms andtheir bulky substituents will hamper effective Van der Waals interaction between the chainsand crystallization. The X-ray diffraction*** pattern of polymer 13 revealed its amorphousstructure. The low-molecular addition compounds 7 and 8 behaved similarly: they failed tocrystallize and showed an abnormally low melting point.

The mechanical properties of the polymers obtained from diphenyltin dihydride are poor.Clear films cast from a chloroformic solution are brittle as are the fibers drawn from a hotmelt of these materials.

The results of thermogravimetric tests on some poly- addition polymers (Chevenard thermo-balance, N2 atmosphere, heating 2.50 per min.) are presented in Table 4****. Temperature

at which 5 and 50 percent weight loss has occurred (T5% and T 5 0 %), residual weight at 9500

(RW) and the percentage of inorganic elements in the original polymer are given. As itappears from these data these poly-addition polymers are, under the conditions employed inthis test, stable up to about 3000C, quite according to expectation in view of the stability ofthe bonds present in these polymers.

The compounds and polymers, containing both germanium and tin or both lead and tin,display in their infrared spectra distinctive "X-sensitive" absorptions associated with the

presence of phenyl- and p-phenylene-MIV groups in the molecule (see also Section VII), therelative intensities of which are indicative of the ratio in which these groups are present.

In Figure 1 these absorptions for MIV-Ge and Sn (bands at 1090 cm- 1 and 1075 cm-1 re-spectively) of four compounds containing both germanium and tin are shown.

1,4-Divinylbenzene (1*) was purified via the 1,4-dihydrobromo derivative (26*). p-p'-Diisopropenyl-biphenyl (2*) was obtained by a Wurtz coupling reaction involving p-chloro-a -methylstyrene (see Section 11-B). The organotin hydrides were prepared as previouslydescribed (Reference 45).

*These measurements were carried out at the Central Laboratory T.N.O., Delft, underthe direction of Dr. D. T. F. Pals.

**These measurements were carried out at the Directorate of Materials and Processes,Deputy of Technology, Wright- Patterson AFB, Ohio.

***The authors are indebted to Prof. A. F. Peerdeman, Laboratory for Crystallography,State Univ. of Utrecht, for the X-ray diffraction measurement.

****The authors are indebted to Dr. G. F. L. Ehlers (Aeronautical Systems Division, Wright-Patterson AFB, Ohio) for these measurements.

8

AFMLj-TR-65-192

a)

IQ.

00 0a) P. a)-ýC

0

4..) 00) 0-44.0 - .

"o t-. c'4 C14

00L

41

E- CYJ ce) 0'

'0

-4

0X

CQC

ccm

00 C~ CM

E-4 (

00a. N( a . c) c -- I C

0

cnNbf -4z

0 N N9

AFML-TR-65-192

L,.

I1 2 3 4-I

1120 1030 Frequency (cm )

Figure 1. Infrared Absorption Spectra (1120-1030 cm- )of: 1. C64H56Ge2Sn (6); 2. C 44H 38GeSn (3);

3. C64H5 6 GeSn2 (9); 4. (C40 H 36GeSn)n (17)

All reactions involving organotin hydrides were carried out under nitrogen in order toeliminate oxidative degradation of the organotin hydrides. Low reaction temperatures (60'-1100) were employed in the polymer-forming reactions in order to prevent disproportionationof the dihydrides leading to mono- and trifunctional hydrides which would act as chain-stoppingand crosslinking agents, respectively.

The progress of the reaction canbe determined very easily by I.R. absorption measurements.-1

The disappearance of the characteristic Sn-H stretching vibration in the 1800-1840 cm region(5.5/1), see References 46, 47, together, of course, with the disappearance of vinyl absorptionbands is the most clear-cut indication that the reaction has gone to completion.

C. Synthesis of Cyclic Monomers and Linear Polymers from Organotin Hydrides andAcetylenic Compounds

As outlined above linear heteropolymers containing tin-ethylenic groups in the main chainmay be obtained from organotin dihydrides and a,w -diynes, such as 1,5-hexadiyne, 1,8-nonadiyne, and 1,4-diethynylbenzene. Such reactions will proceed via the intermediate forma-tion of a compound (A) containing a tin-hydrogen, a carbon-carbon double, and a carbon-carbon triple bond:

10

AFML-TR-65-192

R2 SnH2 + HC-CR'C-CH -t H-Sn-CH-CH-R'-C- CH

(A)

[n-CH=CH-R'- CH=CH] (X IV)

(B) 33-37, R' = (CH 2 ) 2

38-39, R' = (CH 2 )5

40, R' =

In general these compounds react with considerable evolution of heat, calling for the useof a diluent. The reactions were carried out initially in n-hexane and finally after removalof the solvent at 1000. In each case investigated the reaction product was soluble in benzene,but the infrared spectrum was completely devoid of residual Sn-H or acetylenic absorption.

The polymers derived from 1,5-hexadiyne range from a rubberlike elastic solid (R = Ph)

to viscous liquids (R = Me, Et, Pr, Bu). When heated in vacuo (150°-250° at 103 mm Hg),the liquid polymers change to rubberlike, benzene-insoluble solids (polymers 33 and 34,R = Me, Et) or to benzene-soluble, elastic near-solids (polymers 35 and 36, R = Pr, Bu).This was accompanied by distilling-off a liquid having the same analytical composition asthe remaining polymer. The absence of Sn-H and acetylenic absorption in the infrared spectraexcludes the open structure (A) for these volatile products. Apparently the primary inter-mediate (A) partly reacts intramolecularly with formation of the cyclic monomer (C):

R SnH2 + HC=C-CH2-CH2-C-CH [H-Sn-CH-CH-CH 2-CH 2 -C CH

(A)

R R C-CH-CH2

-Sn-CH-CH-CH 2 -CH2-CH-CH] + Sn (XV)Rn R7 CH'-CH-CH2

(B) (C)

This picture is in accordance with the infrared characteristics observed in the spectra of

the cyclic monomers: presence of the v C = C absorption band at 1590 cm-1 and the ring

vibration at 785 cm-1 (see also Section VI-C), absence of the strong trans-vinylene absorption

11

AFML-TR-65-192

-1present in the corresponding polymers at 987 cm . The 2,6-cycloheptadiene derivativesisolated are presented in Table 5. The polymers obtained in Reaction XIV are presentedin Table 6.

The reactions of diphenyltin dihydride with 1,4-pentadiyne-3-ol (43*) and with 3-phenyl-1,4-pentadiyne-3-ol (44*) afforded brown brittle polymers, which, owing to partial re-sinification of the diyne, did not have the correct composition. Derivatives of 1-stanna-2,5-cyclohexadiene could not be isolated. Similarly, only polymeric products were ob-tained in poly-additions involving 1,8-nonadiyne (45*).

The hexadienyltin polymers show some structural resemblance to natural rubber. Apartfrom the presence of methyl groups, every second -CH 2 CH2 - group in natural rubber has beenreplaced by a dialkyltin or a diphenyltin group:

RI[CH2 -CH-CH-Sn -CH-CH-CH 2 -

R

[ C 3 CH3 ]-CH 2 - C-CH-CH2 - CH 2 -C=CH-CH 2 -

n

Replacement of the ethylene group in this type of organotin polymer by the pentamethylenegroup results in the loss of the rubberlike properties. All efforts to vulcanize this "tin-rubber" using several vulcanizing systems have been in vain, whereas this polymer, asappeared from oxygen-absorption measurements, will not be very suitable for purposesin which oxidation-resistant rubbers have to be applied*. The results of a thermogravi-metric test on this polymer has been presented in Table 4.

Molecular weights of the benzene-soluble polymers, determined by means of ultra-centrifuge measurements** are presented also in Table 6. As might be expected, the de-grees of polymerization of the polymers obtained by diyne-dihydride poly-additions areappreciably higher than those mentioned in the previous section dealing with dienes.

Although trialkylgermanium hydrides have been reported to add quantitatively to terminalacetylenes (Reference 48), only low-molecular-weight polymers resulted from the reactionof organogermanium dihydrides and a -w-diynes. In spite of the rather drastic reactionconditions (7 days at 1200 without a solvent; chloroplatinic acid catalysis), the polymersobtained from diphenyl- and dibutylgermanium dihydride and 1,5-hexadiyne displayed residualGe-H and acetylenic absorption in their infrared spectrum, indicative of a low degree ofpolymerization. The phenylgermanium polymer (42) showed none of the rubberlike properties

*The authors are indebted to Dr. J. W. H. Zijp and Mr. G.A. Gerritse of the Rubber Institute,

T.N.O., Delft, the Netherlands, for carrying out these measurements.

**These measurements were carried out at the Central Laboratory, T.N.O., Delft, the

Netherlands, under the direction of Dr. D. T. F. Pals.

12

AFML-TR-6 5-192

a)

w aer4 C.4 .4 .4 -4 041

0 0M I %

7M 0 0 r-4 cc c'J C

C4)0CA .4 0 0

04AC LA LA LA '.0 .n

b) v.4

%0 v4 C4 V.4 r-4

0i -A I I I

""4 0 0e0ncd ~0 o *. .

!4 1 ~ A0 0 0 LE C) to ' '0 L C

'0 I

4 '- 0 -~ 04 -t 0

.v1 C) 9A N- a) ~ ,- -

CC)

r- 0-4 m' 0' .4 C14

cc C1 C4

C14

v-I CV) ,-

'-4 ____ ____ _____13

AFML-TR-65-192

v-I V-4 v-I v-I a q v- -I v-IC~~ CID~~

oo M ao aY a a o

u-o c ~ Cv cq c'q 00 cq01 N q

ui C> C> D C

LO iO t-oC to oc r- -

CD0

m 0 0 0 0

C)d

-- j

4v-I

V - 0 a

o) 0Cd C)

00

0) 04 C) .dC

4 C.0

C-~ -4 a1~

0 0 () )0 .

co CO) 0~C)

o00*r 04 0o 0C C) OD 00

C)

100

o v-4

=E4 () v-0 v-I coI v-I v- C vI

C) D

C)

CD t- 0m l I I lot m ID.Y Iv C

-~ C114

AFML-TR-65-192

of its organotin analogue. Attempts to demonstrate the presence of the cyclic monomer inthis polymer were unsuccessful, whereas on heating the butylgermanium polymer (41) invacuo a small quantity of the cyclic monomer (32) was isolated.

Similarly, both cyclic dimers and polymers may be expected from the reaction of organotindihydrides and monoacetylenic compounds, such as phenylacetylene. However, in these studiesno attempts have been made to separate the six-membered heterocycles (compare Equation VI)from the reaction products. The isolation and characterization of the cyclic dimer from di-phenyltin dihydride and phenylacetylene had been reported previously (Reference 41).

The first step, i.e., the formation of a B-styryltin hydride (D) proceeds exothermally; thesucceeding polymerization requires prolonged heating at 90°-130°:

R RRSnH -+- HCCPh--- H-Sn-CH=CH-Ph [-n-CH2 H (XVlR2 Sn 2 2-C1~h(XI

R Ph

(D)

46-48, R = Pr, Bu,and Ph

The low-molecular weight polymeric products thus obtained are listed in Table 7.

Phenylacetylene, 1,5-hexadiyne, 1,8-nonadiyne (45*), and 1,4-pentadiyne-3-ol (43*) wereobtained according to published methods (compare Reference 24). 3- Phenyl- 1,4-pentadiyne-3-ol(44*) was obtained from the reaction of ethynylmagnesium bromide with phenylethynylketone.p-Diethynylbenzene (49*) was prepared from crude divinylbenzenes via the p-tetrabromoderivative (50*). Diphenyl- and dibutylgermanium dihydride were obtained by LiA1H4-reduction

of the respective halides. Dibutylgermanium dibromide (51*) was prepared from diphenyl-germanium dibromide via dibutyldiphenylgermane (52*).

D. Synthesis of Low-Molecular and Polymeric Adducts from Organotin Hydrides andVinyl Derivatives of Group IV Metals Containing the p-Phenylene Group

As discussed in Section I-A reactions involving organotin dihydrides and divinyl-organo-metallics will result mainly in the formation of cyclic products. With this in mind some divinylderivatives of a novel type have been synthesized according to:

R R2 R2 MVCI 2 (excess) + BrMg gBr - CIMIV .MIVCI (XVII)

R K

53*-556*, MIV = Si or Sn

R= Me or Ph

15

AFML-,TR-65-192

Q) 0ýc

u- cn'0- 0ý -

w) c*1 cI

0214J

aa)

0)-0

a OD

E'-4

b1>1

00

(n "4-. -'-4

<0 Wr *-

C.-

4-1 (1)' cc.

004-1J

0 P4.

Z t qt -

16

AFML-TR-65-192

R R R RIIV -I-2 CH CHMgBr H -C=CH-MV IV-cH-CHCIM .. ~ MI/I+ H Q~~ H

R -R 2RR(XVII I)

56-58, MIV = Si or Sn

R = Me or Ph

These compounds, which have been listed in Table 8 were expected to yield solely linearpolymers upon reaction with organotin dihydrides as a result of the presence of the p-phenylene group. However, reaction of these compounds with triphenyltin hydride, althoutihaffording the expected products (see Table 9):

R RPh SnH + CH2-Q"'IV

3 HCH-M M-HC

R R

R RRIV.. Q4MI V~cH2CHSnPh

Ph Sn-CH CH ,1V (XIX)3 1-C 2 -M

59-61, MIV = Si or Sn

R Me or Ph

was accompanied by some decomposition. Reaction with diphenyltin dihydride did not produceproducts with any appreciable molecular weight, considerable evolution of gas, and formationof metallic tin being observed. Apparently the p-phenylenedivinyl derivatives are susceptibleto the reducing action of the organotin hydridesi.

E. Synthesis of Low-Molecular and Polymeric Adducts from p-Phenylene-Bis(DimethyltinHydride) and Olefinic and Acetylenic Compounds

As described in the previous sections organometallic polymers having appreciable molecularweights can be obtained by means of poly-addition reactions involving organotin dihydridesand unsaturated compounds. However, the softening points of these polymers are low. Onepossible way to increase the crystallinity, and with that the softening temperatures, of thesepoly-addition polymers is by introducing an enhanced rigidity into the polymer backbone.This may be accomplished by introducing p-phenylene groups into the polymer backbone.The phenylene groups may form a part either of the dienic compound or of the tin hydride.Poly-addition reaction using several dienic compounds containing the p-phenylene grouphave been described in previous sections. Poly-addition reactions using p-phenylene-bis-(dimethyltin hydride) are described in the present section.

p-Phenylene-bis(dimethyltin hydride) (62*) has been obtained by reduction of the cor-responding dichloride (55*):

17

AFML-TR-65-192

u-i

u-i

P4 4 -

LU c

-44 m4

C)

-o -q 000co to m

m) CY) 10

c.; c'

-5 c. c\q

m~ LO~ ý. IO

F4~ c.C9 cq~ C11 C) 0 0C) LoI t~- LO

=Ecn co cn cC= C1 D C1

u u-4 CI y.0

ZI C

0M 0

CC C

4 = 0C., - I

-ME-

C) -

MEM

CL.

LO toiC C.0

~, ~ 08

AFML-TR-65-192

Me __ Me Me _ Me

CI-Sn Sn-CI L -- H-SSnQ n-H (XX)

Me-"Me Me Me

(62*)

For an insight into the reactivity of this hydride a few model reactions were carried outwith mono-p-styrenyl derivatives of germanium, tin, and lead. The 2:1 addition productsobtained are listed in Table 10:

Me Me

H-Sn Q 'Sn-H + 2 RMV Q CH=CH2

Me Me

/• Me/• Me /

SRM CH2-CH-CH2-CH M R3 (XXI)

3 2SMeG MeS

I Iv

63, R = Me MIV = Sn

64-66, R = Ph MIV = Ge, Sn, and Pb resp.

Since each tin atom of the present organotin hydride bears two aliphatic groups the be-havior of the compound towards unsaturated carbon-carbon bonds much more resemblesthat of alkyltin hydrides than of aryltin hydrides. Therefore fairly long reaction periods arenecessary to complete the addition reactions. The 2:1 adducts are colorless amorphous solidswhich show a wide melting range. Repeated crystallization from appropriate solvents did notyield sharp-melting, crystalline compounds, although according to analytical and infrareddata these solids must be fairly pure. Lack of crystallinity, which also is encountered in theaddition products 7 and 8 (Table 1) seems to be inherent to this type of molecules.

19

AFML-TR-65-192

4)cqI cq

LU q eqIC1

0

LU~Ul * 44 i)

CD) 0

0) _e 1-4

I I I

a) 4C>)4P

w) 00 CD

> LU1

0 , eq eqk

CD q '4Ne

-J z~ 0

> eq q el eq 4btot t -

0

eq eq q eq

P4 ul

eq eq eq eq

I J-e C)4 cq cq cqIf U

1eq 1eq eq eq

Ci,4 0

k -P 0pq CO) Q)C)

4.))

ro

or -T ~toL. T0

P4 Cl) 020

The poly-addition reactions of p-phenylene-bis(dimethyltin hydride) with several dienic,acetylenic, and diacetylenic compounds afforded polymeric products which showed closeresemblance to the corresponding polymers derived from diphenyltin dihydride:

Me Me

H-Sn O MSn-H + CH CH-R-CH-CH2

Me Me

MeMe

-Sn "(C /h Sn-CH2 -C H CH (XXI,)I I - 2 - 2

Me Me n

Ph_67,68 R = IV

•--OPh

69,70 R = , resp.0 0

Me _ e Me Me Ph

H-Sn n-H + HC-CPh Sn Sn-CH -CH-I (XXI II1)

MSe - e L e -- •le Ph

(71)

Me _ Me Me Me

H-Sn •n-H + HC=C-R-C--CH -- -Sn Sn-CH -CH-R-CH =CI I IMe •- Me Me •- Me

72-74 R 2(CH 2 2- -(CH 2 )5 - and (XXIV)

O resp.

21

A survey of the polymers thus obtained is given in Table 11. The polymers 67, 70, 72, and73 have been subjected to molecular weight determinations by means of ultra-centrifugemeasurements*.

Exact molecular weights could not be determined by this method, due to a very broadmolecular weight distribution of the polymer sample. The weight-average molecular weightsof all of these four polymers are about 100.000 (ii = -120-200). It has to be stressed that theexperiments indicate that only about less than 10 percent of each sample has a molecularweight of a few hundred-thousands, whereas the bulk of the samples has a molecular weightof approximately only a few ten thousands.

In spite of these rather high molecular weights the softening points of the above describedpolymers just like those of the polymers obtained from organotin dihydrides, are low. Ob-viously this unfavorable behavior is inherent to this type of organometallic poly-additionpolymers. This may be due to the absence of intermolecular forces, which is also demonstratedby the lack of crystallinity of several monomeric compounds. Hydrogen-bonding can not occurand van der Waals interaction between the molecules will be hampered by the bulky organo-metallic group.

F. Synthesis of Polymers from Organotin Dihydrides and Unsaturated Esters and Amides

Another way to increase the melting point of polymers is by favoring chain interaction byintroducing polar groups into the polymer main chain. To this purpose organotin dihydrideswere reacted with difunctionally unsaturated esters and amides.

The poly-addition reactions of organotin dihydrides with ethyleneglycol diacrylates,methacrylic anhydride, allyl methacrylate and diallyl diglycolate yielded tin-containingpolyesters: R

R2 SnH2 + H2 C-C-R' ''-CCH2 P- -Sn-CH- 2-CH'R'] ' (XXV)R' R" LR R' R

75-79, R"' = organic group containing at

least one ester (anhydride)

function

*See Reference 44 and footnote on page 8.

22

AFML-TR-65-192

w. 04 eq eq eq

eq eq V- q eq

u- iq rI -

am aO -O aO aI

v-I , v-I v-I ~4 v-

UI (

= 0 o .4

U,

"q 0) C1 0) c qc

-,d4 U)4 0 m 1-q

CCo

0)

Cd eq

~4001 - 4 -04c

e q e

w, o-q eq eq eq Ie I

I~j C= c q cqecq eqq

0o

tq eqmT- q e

CD to U1 - t -- L

I 23

The weight-average molecular weight of the polyesters determined by means of the Archibaldmethod (Reference 44) was found to be 150.000 (n =320, polymer 76), 25.000 n =60,polymer 78), and 75.000 (n- = -150, polymer 79).

Upon heating diphenyltin dihydride with N,N'-alkylene-bis-acrylamides low-melting brittlepolymers soluble in dimethylformamide were obtained:

Ph2 SnH2 + H2 C-CH-CO-NH-(CH 2 )X-NH-CO-CH-CH 2[PhIr'_----- Sn-CH2 -CH 2 -CO-NH-(CH 2 )X -NH-CO-CH2-CH2 ] (XXV I)

Ph

80-82, x = 2,6 and 9

The polymers obtained in Reactions XXV and XXVI are listed in Table 12.

The N,N'-alkylene-bis-acrylamides (83*-85*) were obtained from acryloyl chloride and thecorresponding diamines. The addition reactions were carried out as described in previoussections.

As may be derived from these and formerly described experiments the addition of the tin-hydrogen group to unsaturated carbon-carbon bonds maybe applied successfullyto the synthesisof high-molecular weight polymers containing organotin groups in the polymer backbone. Inspite of the rather superficial characterization of the polymers obtained in this syntheticstudy, we believe, however, that it may safely be concluded that polymers, obtained in thisway, in general will be very viscous liquids or low-melting solids. Interchain forces in-evitably tend to be very weak as a consequence of the presence of the bulky organotin groupin the polymer main chain.

24

AFML-TR-65-192

eq cq cq eq ol oq

0 C; 0 C; eq;

to to m

i-I K: -

I- I I I I N

-5-

oc

Fp4 I I

'0 bD a) a

bD0 m m) m

;q tv CV cq Uý q eq eq

0~ 00 0 0 0 Z Z zto C.0 eq eq to eIi q 00

bOeq eq eq eq eq eq m~ m'

' c~ q 0 o c q Qr- eq eq ,-q eq eq eq eq

00 0 0000

0q 0-

0e0 0 z

0 0I~~ eq0

~ 0 0 0q cS0 0 z g

P. eq eq eq P, P

a =) w eq00 0 V0 0 q

t- 00 0o 0

0 0 eq q Z 25

AFML-TR-65-192

SECTION II

PREPARATION AND POLYMERIZATION OF GROUP IV ORGANOMETALLICDERIVATIVES OF STYRENE, a -METHYLSTYRENE,

ISOPRENE, AND ACRYLIC ESTERSA. Discussion

When this program was started it was decided to synthesize a number of Group IV organo-metallic derivatives of styrene and a -methylstyrene and to study their homopolymeriza-tion. Vinyl-type polymerization of these monomers will lead to carbon-chain polymers withorganometallic groups attached to the main chain:

I IC= CH 2 -- H 2-

M------ (XXVI I)

MIV RMI3 MRI - n R' = Me or H

Similarly, homopolymerizations involving Group IV organometallic derivatives of isopreneand acrylic esters may lead to polyisoprenes and polyacrylates in which the metal atomsare attached directly to the polymer main chain:

Me Me, IHC=CH-C-CH - - =CH-CH C-CH2- (XXVIl1)

COOR' r COOR'I IlHC=CH - -HC-CH- (XXIX)

I ISnR 3 SnR3

B. Synthesis of Group IV Organometallic Derivatives of Styrene and a-Methylstyrene

The triphenylmono- and diphenyldi-p-styrenyl derivatives of germanium tin and lead wereobtained by interaction of p-vinlyph~nylmagnesium chloride (Reference 49) with the ap-propriate organometallic halides:

Ph4n MIVXn + n CIMg-0 CH-CH2 -- Ph4 n MIV ( )CH-CH2 )n

(XXX)

86-91, MIV = Ge, Sn,and Pbn = I ond 2

27

AFML-TR-65-192

Triphenyl-p-styrenylsilane, due to steric factors cannot be obtained in this way. Attemptsat synthesis-via the reaction of p-chlorostyrene with triphenylsilyllithium (Reference 50)were also unsuccessful (Reference-21). The compounds 86-91 have been listed in Table 13.

Trimethyl-p-styrenyl and trimethyl-p-a-methylstyrenyl derivatives of silicon, germanium,tin, and lead were obtained in the same-way (see also Table 14):

IV IMe3MI X + ClMg-C=CH2 - Me3 MIV C=CH2 (XXXI)

93-100, MIV = Si, Ge, Sn, and Pb

R = H or Me

p-Chloro-a-methylstyrene (101*) was obtained by dehydration of p-chlorophenyldimethyl-carbinol, prepared from p-chlorophenylmagnesium chloride and acetone.

p-Tert-butylstyrene (92), which has been included in our polymerization experiments, wasobtained by dehydration of p-tert-butylphenylmethylcarbinol (102*).

Infrared spectra of these compounds revealed, aside from the bands associated with thepresence of the p-phenylene and either the phenyl or the methyl groups (see Section VII),S--1bands characteristic of the vinyl groups, e.g., at 910 cm (strong, = CH 2 deformation out-of-

plane at 988 (medium strong, -CH out-of-plane deformation) and at - 1625 cm-1 (weak, C= Cstretching). Contrary to previous assignments (Reference 21, 22) the band occurring near

1380 cm-1 must be attributed to C-C stretching vibrations of the 1,4-disubstituted aromaticnucleus (see also Section VII).

C. Homopolymerization of Group IV Organometallic Derivatives of Styrene and a-Methyl-Styrene

The styrene monomers 92-96 polymerized readily at 70'-90° in the presence of free radicalinitiators, preferably 2,2'-azo-bis-isobutyronitrile to give the polystyrenes 103-107:

CH =CH2 -CH-CH 2 -

(XXXII)

MIVMe 3 M IVMe 3

103-107, MIV = C, Si, Ge, Sn, and Pb resp.

These are clear, colorless solids, soluble in aromatic solvents and chloroform. The organo-lead polymer, provided its molecular weight is high enough, only swells in these solvents.Thermal polymerization is also possible but this requires prolonged heating at -140'.

28

AFML-TR-65.-192

US

v- -IvI -

Lu

CD - a a l.toe v~ c~ e

a) 0.0

v- -I iI - vI Q

0p eq 00aq -J -l 04v4 f 0

LU v-4 v.4 v-4 v-4 v

ci- -ot 0 0 0C> cq cq c cq c N 0

LUQ

-a

09o

00 00 0 0

CV) ~29

AFML-TR-65--192

C6,

ei q cqaeq N~

cq4 Cq~ eq a q eq eq eqeq eq eq c4.4 q eq eq eq

cz

C=

- O0 CD 00 U) to Ce Coa. CO t- m Ce dO"

> o CD 0 q 00 m~ t- 01.4 1-4% Ci tC- Oý ot eq 1

04 0 a 1-4 1-4 V4 0D "-q H- H

0

o 'm - 00 00 mo0 C) -" 1 Ow C4 c CD eq It~ 0 4 t to eqoeq eq t~ o o q m~ 10) m) Go

>1 LO 0 IL, 1 O LO to 1a LO LO t 0 CX0

Z:-4 i-4 ,.4 9 1-4 r4 1.4 r4 r40

00eq4

ce)~e aq H 'r-4a eq C)COL

C> CO CoC q .4 t5-i oo 0 0DC) C) 0c 0D(Dc

pqe CD o I; I- C- 1--0, 1-4 13c

m U)I r- CD t C-4 c i- 0 03 0 0 010 ~c cl 1~ 1 O C 0 m0 C

m-(l 0 CO 0 w O to LO

--

0 r-

0) r-4 1-4

P~0 4 pq m C) r4-o ýo 00 OD4 0 OD m I H

ME1IV- -4 1-4 1-4 ?-I V14 1-4

= q -4 H- H4 c4 q eq eq e""q 1- -4 1- 14 1-4 V-4 1-4 1-4 r4 . 0 .0d 0 0) 0 0 U 0 0 0 - -= --q c4 q eq

10 10 10)

U)) C) a) C

C12U) ) ) U 54 5-4 9-

4-b

0 00 0

S-Ij 4 0g 04H~~ P4 ... c 0 ,4)ci .

m a aj m m m C)

30

AFML-TR-65-192

A rather interesting dependency was found to exist between the nature of the metal atom andthe rate of polymerization. A quantitative study revealed the sequence Pb > Si > C > Ge > Sn(see also Figure 2).

70 woS "

0 Sn

4 50

W 40

-jo 30a-

20

10

1 2 3 4 5 6 7 8 9

TIME IN HOURS

Figure 2. Plot of Percentage Polymerization Against Time for

Monomers p-Me 3 M IVC6 H4 CH CH2 (70.00; 0.10 Mole %

2,2'-Azo-Bis-Iso-Butyronitrile)

Homolytic cleavage of lead-carbon bonds during polymerization, providing a source of extrachain-initiating radicals, is probably responsible for the higher rate of polymerization of thestyrenyllead monomer:

C vCHw2

PbMe 3

---"H •c2 0° (xxI

(XXXIII)

0

31

AFML-TR-65-192

A consequence of the phenomenon is the formation of a crosslinked polymer. The sequenceSi > C > Ge > Sn is best related to a decreasing electron-attracting effect of the organo-metallic substituents. It might be that for silicon electron-attraction as a result of dlr-p7r

interaction with the styrenyl group surpasses the effect of electronegativity which decreasesin the order C, Si, Ge, and Sn. Korshak et al. (Reference 53) have found a similar sequenceSi > C > Ge > Sn for the polymerization of vinyl-substituted organometallics. RecentlyPolyakova et al. (Reference 54) reported a similar sequence for the degree of polymerizationof Group IV substituted polystyrenes, obtained by radical-initiated polymerization underhigh pressure.

The polymer containing silicon, germanium, and tin has a softening point in the range of170°-180' and, in finely divided form, can be pressed into transparent colorless films or

sheets at elevated temperature (-190°) and pressure (-200 kg/cm 2). The brittleness ofthese films decreases in the order Sn > Ge > Si.

The thermal stability of these carbon-chain polymers is determined by the temperatureat which the depolymerization reaction starts. In Table 15 the results of a thermogravi-metric analysis (heating in air at a rate of 50 per min.) are presented. From these figuresit appears that the order of stability of these polymers is Si %Z Ge > Sn > Pb > C (see alsoReference 55).

Copolymerization experiments involving Group IV organometallic styrenes have recentlybeen reported (Reference 56). Similarly, p-trimethylgermyl-,p-trimethyltin- and p-tri-methylleadstyrene in the presence of 2,2'-azo-bis-isobutyroniFrile readily copolynierizewith styrene and methyl methacrylate to give glasslike copolymers.

The organometallic derivatives of a -methylstyrene listed in Table 14 do not undergothermal or radical-initiated polymerization under ,the conditions given for the styrenemonomers, whereas the triphenyl-substituted derivatives listed in Table 13 readily undergoperoxide-initiated polymerization to give transparent, rather brittle, glasslike polymers.Recently the radical-initiated polymerization of Group IV derivatives of a-methylstyreneunder high pressure (6000 atm.) has been reported (Reference 57).

D. Synthesis and Attempted Polymerization of Group IV Organometallic Derivatives ofIsoprene and Acrylic Esters

To obtain a polymerizable organotin-substituted isoprene first triethyltin hydride wasreacted with ethynyldimethylcarbinol:

Me

Et 3 SnH + HC--C-CMe2 OH so Et 3 SnCH-CH-C-OH (XXXIV)

Me

(IO8*)

However, all attempts to dehydrate this compound have been in vain.

An alternative route, i.e., dehydration of the acetylenic carbinol followed by the additionreaction with triethyltin hydride was also unsuccessful. The addition reaction did not proceedin an unequivocal way, a mixture of the 1:1 and the 2:1 adduct had been obtained the separationof which could not be fully achieved:

32

AFML-TR-65-192

al0.

4J4J C) C -. m . r0 -

02

r-4 cd -

4Ja 00 0 ' c0 r P ' cc .

a *-f4 o.

1-4 W ) C C

-4r-

0 4

0 Cd'-'c C C01 0 o 0 0 0

boH

r~ 0

(D -411

o 0a4)

o L H~b Q.) 0-- I1

-- 4

-t1

C) Hz -4C- 4 . -

a33

AFML-TR-65-192

OH 3CH3

Et SnH + HC--C-C-CH 2E 3 SnCH-CH-C-CH2 +

(109) CH'O3+ Et SnCH=CH-CH-CH.SnEt ) [XXXV)

( 110*)

Similarly, the reaction of triethyltin hydride with 1-methoxy-i-buten-3-yne failed to givea pure product:

Et 3SnH + HC--C-CH-CH-OCH 3 Et SnCH-CH-CH=CH-OCH (XXXVI)

( III*)

The fraction obtained after several fractionations still contains some 2:1 adduct.

To obtain trialkylstannyl derivatives of acrylic esters trialkyltin hydrides were reactedwith propiolic esters. However, the course of the reaction is not unambiguous. Besides theaddition of tin hydride across the triple bond (see also Table 16) substitution of the acidichydrogen of the acetylenic part of the propiolate by the trialkyltin group also occurs. Thelatter yields trialkylstannyl derivatives of propiolic esters. The tin-ethylenic bond in thecompound thus formed is easily hydrolyzed producing the organotin hydroxide and propiolicester. These two compounds may react with each other to give the trialkyltin salt of propiolicacid. Model reactions of organotin methoxides and hydroxides with propiolic esters confirmedthis picture.

R 3SnH + HC=-C-COOR' - ,- R Sn-CH=CH-COOR' (XXXVII)

112-115, R = Me, Et

R' = Me, Et

R3SnH + HC--C-COOR' - R3 Sn-C=C-COOR' (XXXVIII)

116 *1 R = EtR'" Me

R 3Sn-C=C-COOR' + H 20 - RSnOH + H-C=C-COOR' (XXXIX)

R 3 SnOH + H-C-C-COR' - HC-=C-COOSnR3 + R' OH (XL)

117*, 118*, R = Me and Et resp.

The homopolymerization of these organotin acrylic esters under the influence of Ziegler-Natta catalysts was attempted, using the following systems:

a. Et 3 Al/VOC1 3 (15:1) or EtAlX 2 /VOC1 3 (15:1) "Bakelite" catalyst

b. Et 3 Al/VOC13 ( 2:1) "Copolymerization catalyst (Reference 58)

c. Et 3 Al/TiC14 (3:1) "Ziegler-Natta" catalyst (Reference 59)

However, in these cases no polymerization was observed.

34

AFML-TR-65-192

r-4 r-4

0).4 C') r-4 c')

0 r-4

A.C4 Cv, .00-4n

Cd'

-4 4J__________

cc 00,--1 -4J -0. 4 -

0) -4 4

,.r'

00

A ---4t -

-u -- ---4-

-A' o 00 \O0 Lv, N.

0 A It A I

'0 dC14 N. . 00d4

-44P-4

0d r 0 00 04 C')

CC 0 -N.4 0O - -

E-

,0:

0

0N crr-I 1- -4I

z -4 1- r-4 ý4

35

AFML-TR-65-192

Acrylic acid with a trimethylsilyl group attached to the a-carbon atom was prepared also(119*). Attempts to synthesize the methyl ester of this acid, involving diazomethane, resultedin impure products. Recently the synthesis (Reference 60) and homopolymerization (Ref-erence 61) of a -trialkylstannylacrylic alkyl esters at high temperatures (-.2500) have beenreported.

36

AFML-TR-65-192

SECTION III

BIS-CYCLOPENTADIENYLTITANOXANE DERIVATIVES OF GROUP IV METALS

A. Discussion

Among the biscyclopentadienyl derivatives of the transition metals, ferrocene especiallyhas excellent thermal stability. It is to be expected that the thermal behavior of certainderivatives of similar sandwich compounds derived from titanium and vanadium will be moreor less comparable. Therefore, the introduction of bis-cyclopentadienyltitaniumor -vanadiumgroups might result in thermostable structures with attractive physical properties. Of themany synthetic approaches which can be considered, the reaction of bis-cyclopentadienyl-

titanium diacetate with a dialkyl- or diaryl-M IV-dialcoholate or of bis-cyclopentadienyl-

titanium dichloride with a disodium dialkyl- or diaryl-M IV-diolate may be mentioned.

0 Cp 0 R Cp R 10I so I I ] o

an + O nR in+ nC -OR

CH3C-O-Ti-O-CCH3 + n R O-M OR + 2 n CH3C-OR'Cp 6, A

(XLI)

Cp R Cp RI I V I IIVn CI-Ti-Cl + n NaO-M -ONa -Ti-O-M -0- + 2 n NaCI (XLII)I I ] Icp R Lcp Rn

B. Synthesis of Triphenylsiloxy Derivatives of Bis-Cyclopentadienyltitanium

The suitability of Equation XLII for polymer formation was studied in a model reactionby reacting monofunctional sodium triphenylsilanolate with difunctional bis-cyclopentadienyl-titanium dichloride in toulene. Contrary to the findings of Gutmann and Meller (Reference 62),who were unable to isolate any condensation product, this reaction afforded triphenylsiloxy-and bis-triphenylsiloxy-bis-cyclopentadienyltitanium derivatives. It was found that dependingon the reaction temperature employed, one or two chlorine atoms are replaced by the tri-phenylsiloxy group:

Cp70*. 1

Ph SiOTiClI

Cp ( 120•)Cp 2 Ti CI 2 +2Ph SiONa (XLIII)

Cp

I-CPh SiOTi OS iPh3

Cp ( 121 )

Tetrakis-triphenylsiloxy-titanium (122*) wias isolated in very low yield from the residueof the reaction at 110%. Neither the formation of compound 120 in the 1100 reaction, nor ofcompound 121 in the 700 reaction could be demonstrated.

37

AFML-TR-65-192

C. Attempted Synthesis of Bis-Cyclopentadienyltitanoxane Polymers of Group IV Metals

The above described route XLI appeared very unpromising due to the extreme sensitivity

towards moisture of bis-cyclopentadienyltitanium diacetate (123*). Moreover, this compoundpossesses marked thermal instability which necessitates the application of a low reaction

temperature in the reaction with a dialcoholate. Reaction with dimethyltin diethylate, ex-

pected to proceed according to:

Cp Me Cp MeI I I I

n AcO-Ti-Qfc + n EtO-Sn-OEt -Ti-O-Sn-O- + 2 n AcOUt (XLIV)

Cp Me L Cp Me nI

(124)

did not result inthe formation of polymeric material containing Ti-O-Sn bonds. Bis-cyclopenta-

dienyltitanium oxide and polymeric dimethyltin derivatives appeared to be the main products.

The successful preparation of triphenylsiloxy derivatives from bis-cyclopentadienyltitaniumdichloride and sodium triphenylsilanolate has led us to study the polymer-forming reaction ofdisodium diphenylsilanediolate with bis-cyclopentadienyltitanium dichloride:

CP Ph Cp PhI I I I

n CI-Ti-Cl + n NoO-Si-ONa - -Ti-O-Si-0- + 2 n NuCI (XLV)I I I ICp p L Cp Ph n

(125)

The reaction of CP 2 TiC12 with Ph 2 Si(ONa) 2 in toluene at 900 afforded sodium chloride and

an orange-yellow solid (125a) with m.p.-180'. Separate analysis for both Si and Ti of thisproduct indicated a Si/Ti ratio greater than 1. Since the disodium diolate most probably isnot sufficiently pure for high-polymer formation, the direct condensation of diphenylsilanediol with bis-cyclopentadienyltitanium dichloride was carried out also:

CP Ph Cp Ph

n CI-Ti-Cl + n HO-Si-OH - -Ti-O-Si-O- + 2 n HCI (XLVI)I II I

Cp Ph L Cp Ph in

(125)

It is apparent that the presence of a HC1-receptor such as an organic base will favor the

occurrence of co-polycondensation. Upon addition of Cp2 TiC12 to a toluenic solution of

Ph 2 Si(OH) 2 , containing an equimolecular quantity of aniline, at 90° yielded aniline-HC1 and

an orange-colored product (125b) melting at- 1550. Analyses of this product indicated a Ti/Siratio greater than 1 (-1.3), which (together with the presence of residual chlorine) mightbe explained by assigning to these compounds an oligomeric structure with chloro-bis-cyclopentadienyl end-groups (nw4).

38

AFML-TR-65-192

To attain higher molecular weights further experiments were carried out under moreforced conditions, yielding a light-tan, benzene-soluble, infusible powder. Elementaryanalyses suggested that appreciable cleavage of cyclopentadienyl-titanium bonds had oc-curred. The high Ti/Si ratio (-1.8) cannot be explained by assuming an oligomeric structurewith titanium end-groups and must be connected with the presence of Ti-O-Ti bonds in thepolymer chain.

39

AFML-TR-65-192

SECTION IV

WURTZ-TYPE CONDENSATIONS LEADING TO GROUP IV ORGANOMETALLIC

OLIGOMERS AND POLYMERS CONTAINING THE p-PHENYLENE GROUP

A. Discussion

The poly-addition polymers described in the first section of this report in spite of theirappreciable molecular weights have low softening points. This was ascribed to the low degreeof crystallinity or even amorphous state ofthesepolymers. It is well known that a high degreeof crystallinity is favored by, among other factors, rigidity of the polymer backbone, afeature that can be promoted by putting inflexible rings, e.g., the p-phenylene group intothe polymer chain. It is inherent to the poly-addition reaction (addition of Sn-H to H 2C=CH-)

that polymers obtained by this reaction contain ethylene groups. Thus, polymers consistingof a chain of Group IV elements linked through p-phenylene groups have to be preparedby other methods. Such polymers should have crystalline properties and thus melt muchhigher than the poly-addition polymers. With a view to the thermal and oxidative stabilityof the silicon-phenyl bond (tetraphenylsilane may be distilled open to the atmosphere at 4300without decomposition; see Reference 63) the silicon-containing oligomers and polymers ofthis type might be expected to have good stability in particular. Although the germanium-phenyl and the tin-phenyl bond are inherently less stable, p-phenylenegermanium and p-phenylenetin polymers will be about the most stable organic polymers which can be devisedfrom these elements anyhow.

Since the Wurtz-type condensation reaction is very well suited to the establishment of

M IV-aryl bonds, this method was selected because of its simplicity and versatility. Eachof the following reaction types might be employed for the synthesis of polymers:

R2M IV x2 + X-O X N

RMIV x2 + R 2 MIV (O X)2 No= _IV0RR MV

R2 M IV(X)0 • •- (XLVII)

The oligomeric members of this class of compounds were prepared by essentially simi-

lar methods and subsequently their properties were studied.

B. Synthesis of Oligomeric and Polymeric p-Phenylenesilanes

The starting materials required for this study were prepared by conventional methods.p- Chlorophenyl-trimethylsilane (126*), bis (p-chlorophe nyl) dimethylsilane (127*), p-chloro-pýhenyltriphenylsilane (128*) and bisýp-chlorophenyl)diphenylsilane (129*) were-preparedusing slightly modified published procedures. Chloro-p-chlorophenyldimethylsilane (130*)was obtained from p-chlorophenylmagnesium chloride and dichloro-dimethylsilane:

41

AFML-TR-65-192

Me.SiCl +CIMg'2 CI - CIMe2Si-OCl (XLVIII)

(130*)

The preparation of p-bis(chlorodimethylsilyl)benzene (53*) and p-bis(chlorodiphenylsilyl)-benzene (54*) has b1en mentioned in Section LD. The isolation Uf the last-mentioned com-pound was accomplished via the di-ethoxy derivative (131*). p-Chlorophenyl-dimethyl-(p-trimethylsilylphenyl)silane (132*) was obtained by Grignard Zoupling of p-chloromag-nesium phenyl-trimethylsilane and chloro-p-chlorophenyldimethylsilane:

Me3 Si-MgCI + CIMe 2 Si CI

- -Me 3i 0SiMe 2 1 (XLIX)

A number of oligomeric model compounds were prepared by the reaction of appropriatecombinations of mono- and bifunctional p-chlorophenyl and chlorosilanes with a suspensionof sodium sand in refluxing toluene.- In each case the expected product was isolated insatisfactory yield (Table 17). Whereas the methyl-substituted p-phenylenesilane oligomers133-137 and the mixed compound 140 are readily soluble in tfie common organic solvents,the very high-melting completely phenyl-substituted products 138 and 139 are sparinglysoluble in boiling aromatic solvents or dimethylformamide only.

The successful preparation of the oligomeric p-phenylenesilanes led us to carry outunder similar conditions polymer-forming reactions of appropriate combinations of bi-functional p-chlorophenyl and chlorosilanes (Table 18). Poly-dimenthyl-p-phenylenesilane(141, 142) Was obtained by two routes as shown in the next equation:

Me 2SiCI 2 + Me Si( ( \ COI2 Me1

2CI Me 2 S,.•GC I L Me

Each of the reactions mentioned in Table 18 afforded polymeric products the analyses ofwhich are in accord with the proposed structure. The formation of Si-Si bonds, which mustbe considered possible in this type of reaction, most probably does not occur. Moreover,Korshak et al. (Reference 65), who recently reported the poly-condensation of a haloaryl-and an odd four haloalkyl-halosilanes under similar conditions, were unable to demonstratethe presence of such bonds in their products, at least by chemical means.

42

AFML-TR-65-192

LIJL C4 eq q eq eq eq eq eq

LU CU. 0 t o t: L Co I0 -0; 0;Co42C 1 C

0-4 0

-4 C> 44 14 ,C= 0C/3 4 v'

00rdCO cea .I r-I Co cq Co

CD m4 C t- ~ m~ 14 I'D em~ Co .-I r-4 V-4 Co CO eq

m~ t- CO 3M 0o co Co Nq-~1- -I ,4 CO CO eq

0

'ID

0d 0

-,, L"

_3 C.

$4 oo -.0'

No C Co co Co1 Co C)

'dc b ' Co 0 90 C

1-4 eqq c~q c 4 c q cr i ~0- -4 -4q-

C11 C.) Cq0 0q 04 0

14 -o Co to Co c

0q U) OD wC4 0

10

0 4) (D a) ~,qCd C4 cq C.N eq4 C) C) 4q

P4~ý5 Cop0 q

C',

P, 04 P0f _) to Co '4' m0 c, C 4

JCo Co Co Co Co Co Co Co4eq ~ ~ ~ ~ -eq1 -4q 4 C 4

eq 0 o Co eq 0 Co43

AFML-TR-65-192

Ci CO Ci Ci Ci COi Ci COi Ci Ci c

00 0 0 0C0 00

w 00 00 0t0o01 r) -4 a) 4 ýqt w0

cc,- q 1-4 eq eq eq eq Nq

L- t~- 0 CD to Ite4 q eq1 eq-. 4 LO ,4 -V t--4 CID 1-4 eq iLO

LO 0 0 to 0 LO IO toeD q .-q 14 00 O4 m 't LoI-- e1 eq eq ,-4 r-4 eq r-4 eq 0- eq

LE C. l .1 cl I I In .1 C0J In 0 I 0 CV) In I ,I

L" 0L In) to m~ n t- r*-4 m) m

eq-4 eq144 4 1 eq4 A eq0-4

-. o0 toI

C14

Co D co Goq U~ Iq CO COIL r- 4 a

_0 eqC))Cl) c.0

_U on-

.0C.0

0- ClD ..-

w Cl)

Cd

cli Cl)0Cl) eq

meGq0

Of z C)

-I~~l - e)Ii 2

0 0.0

00 .Id4

C= CO

U ý In P, . P

4)p : )j

a) ID a)) a)

C * 0 C)

C0.0 C ' Cd Cd a. 0 0 10.

e - q eq In CD w-4 -4 r-4 4- 4 -

44

AFML-TR-65-192

The polymers are soluble (144a and 145a sparingly) in hot aromatic solvents (with theexception of 146a, compare compounds 138 and 139), but insoluble in aliphatic hydrocarbonsand alcohols. They were obtained as colorless powders by preparation with methanol fromtheir toluenic solution or as amber-colored, brittle resins by evaporation of the solvent.

The poly-p-phenylenesilanes contain on the average only 10-30 p-phenylene groups permolecule. It would seem that the attainment of high molecular weights is hampered by thelimited solubility of this type of compounds, resulting in the precipitation of already relativelylow molecular weight species from the reaction medium. The choice of toluene, one of thebest solvents for this type of polymer, as the reaction medium has the disadvantage that itmay undergo metallation by reactive organosodium derivatives such as phenylsodium to givebenzylsodium (Reference 66). When it is assumed that this type of poly-condensation involvesthe intermediate formation of organosodium derivatives, reaction of the latter with the solvent,i.e., toluene, instead of with a chlorosilyl group will result in chain-termination by each of thetwo following consecutive reactions:

I - I-S Na] + C ---0

-Si + ,H + ,(LI

-Si-Cl + CH2No -Si-CH + NaCI (LII)

Thus, instead of p-chlorophenyl and chlorosilyl end-groups the polymer would contain phenyland benzyl-silicoc7 end-groups. This mechanism of termination which would seem to preventthe attainment of appreciable molecular weights finds support in the observed low residualchlorine content of the polymer fractions isolated; e.g., polymer 143 with Mn = 2400 (ebul-

lioscopic) contains 0.39 percent residual chlorine, whereas the calculated value assumingtwo chlorine-containing end-groups is 2.95 percent. The presence of siloxane groups likelyto result from the hydrolysis of chlorosilyl end-groups could not be detected by infraredspectroscopy. The infrared spectra of the polymers were compared with those of the cor-responding model compounds mentioned in Table 17. The spectra support the proposedstructure, differences occurring in the relative intensities rather than in the position of thevarious absorptions (compare also Section VII).

A first insight into the thermal behavior of some representative poly-p-phenylenesilanesamples was obtained by determining with a Chevenard thermobalance thie weight-loss oc-curring on heating the samples gradually and continuously up to 900' at a rate of 2.5/mrin.under nitrogen*. The temperature at which loss in weight starts and the percentage weight-loss at various temperatures between 4000 and 900' are presented in Table 19. Some typicalweight-loss curves are shown in Figure 3.

*Thermogravimetric curves were determined by Dr. G. F. L. Ehlers (Nonmetallic Materials

Laboratory, Aeronautical Systems Division, Wright-Patterson AFB, Ohio) and at the Institutefor Physical Chemistry T.N.O., Utrecht, under the direction of Dr. W. M. Smit.

45

AFM L-TR-65-192

Cd, C9

_CD C14 CD co to to C;eq r-4 eq eq cq eq -

eq -g ~ i q eq Vq ,4

00 t- ce) t- to m0 O

C,:

bD =o CD cu- cq i-o 0f 0

I--

- ~ e 14 O r-q I t-J

Cq 1-4 eqLOe

0 LAi

bD 1ý,

4) ~ ~ 44 e~ Co c ~ 144 ~ C

CD C

0 uLLJ

H -1

.144

t) CD to to r

C4 cq eq eq C

p 4 I .. ML CD -- DI- I- V- I

o 46

AFML-TR-65-192

WI

500

25141a•143

01450-- 146b

0 200 400 600 800

TEMPERATURE ([C)

Figure 3. Plot of Weight-Residue against Temperature(Heating Rate 2.5°/Min.; N2 Atmosphere) for SomePoly-p- Phen3lenesilanes

All samples show no loss in weight whatever during the initial heating period, then a rapidweight-loss over a narrow temperature range occurs to give an apparently stable residue,which in addition to silicon must contain other elements in view of the considerable remain-ing weight-percentage (e.g., 144a, 145a, 146a).

It is our opinion that the present type of thermogravimetric data should not be interpreteddirectly in terms of thermal stability. We believe that the thermal stabilities per se of allthese compounds having in common a p-phenylenesilane backbone do not differ much; so,there must be other factors which de-ermine the marked differences in the thermal be-havior between the several samples. Among these factors volatility, in particular of lowmolecular constituents of the sample, must be mentioned first.

The the r m a 1 behavior of four samples of a p-phenylenesilane, having the structure(-C 6 H4 SiMe 2 -)n and differing only in degree of polymerization, are shown in Figure 4.

With increasing degree of polymerization the temperature of initial weight-loss shiftstowards higher temperatures, whereas the weight-percentage of the ultimate residue re-maining after heating up to 9000C, increases. The pure pentamer (137, n = 5) starts to loseweight at 3250C, but weight-losses at temperatures of 4000 and 5000 C are 55 and 80 percentrespectively. The pure trimer (135, n = 3) starts to lose weight at 2450C and the weight-losses at temperatures of 4000 and 5000C are 90 and 97 percent respectively.

These facts seem to support our concept that in addition to thermal degradation, volatilityof the sample must also play a part.

47

AFML-TR-65-192

'I

1001

o |I,," 50i- r Me " ,.. n 28

r,,.,... n = 13

Mie n25

- 137 n 5141a \142b 3

.-.-. = 135

0 200 400 600 800

TEMPERATURE (OC)

Figure 4. Plot of Weight-Residue against Temperature(Heating Rate 2.50/Min.; N2 Atmosphere) for

Four Samples of a Poly-.p-Phenylenesilaneof Different Molecular Weights

C. Synthesis of Oligomeric and Polymeric p-Phenylenegermanes

The starting materials required for this study were prepared by a conventional Grignardsynthesis or a coupling reaction with _p-chlorophenyllithium. p-Chlorophenyltrimethylgermane(147*) was prepared from trimethylgermanium bromide and p-chlorophenylmagnesiumchloride; bis(p-chlorophenyl)dimethylgermane (148*) was obtained by the reaction of di-methylgermail-um dichloride with p-chlorophenyllithium. An attempt to synthesize p-chloro-phenyldimethylgermanium chloride (149*) from p-chlorophenyllithium and dimethylger-manium dichloride (1:1 ratio) yielded only impure bis(p-chlorophenyl)dimethylgermane.The wanted compound was obtained, however, from p-5hlorophenylmagnesium chlorideand dimethylgermanium dichloride:

Me2 GeCI 2 + CIMgOCI - CIMe2GeOCI (LII,)

(149"*)

p-Bis(chlorodimethylgermyl)benzene (150*) was synthesized according to:

48

AFML-TR-65-192

2 Me2 GeCI 2 + BrMgoMgBr - CIMe 2Ge-G ý-eMe2 CI (LIV)

(150*)

This compound was purified via the polymeric oxide.

A number of oligomeric model compounds were prepared by the reaction of appropriatecombinations of p-chlorophenyl- and chlorogermanes with a suspension of sodium sand inrefluxing toluene Trable 20). The yields obtained in these model reactions are similar to thoseobtained in experiments leading to the silicon analogues (preceding section, Table 17).

These results induced us to carry out afew Wurtz-type condensations involving bifunctionalp-chlorophenyl- and chlorogermanes (Table 20):

RGeCI 2+ M2 e G O2-o Ge0 (LV)

R Me

154, 155 R = Me or Ph

Polymeric products, which, according to analytical and infrared data, have the proposedstructure, were obtained from the reaction mixtures. Similar poly-condensation reactionsinvolving p-chlorophenyldimethylgermanium chloride yielded only small amounts of low-melting products:

[e

[men

(156)

The polymers 154 and 155 obtained in this way, contain on the average only ten p-phenyl-enegermane units per molecule. Again the attainment of high molecular weights may behampered by factors as limited solubility of the polymeric products formed or chain-termination via metallation of the solvent. The absence of reactive end-groups, as appearsboth from elementary analysis (e.g., C1, found: 0.16%; calcd. for CI(GeMe 2 C 6 H4 )1 2 CI:

3.20%) and infrared spectroscopy, suggests that the previously formulated mechanism ofchain-termination (Section IV-B) also applies in this case. The presence of any Ge-Gebonds could not be demonstrated by chemical means.

D. Attempted Synthesis of Oligomeric and Polymeric p-Phenylenestannanes

The starting materials p-chlorophenyltrimethyltin (157*), p-bromophenyltrimethyltin (158*)and bis(p-chlorophenyl)dimethyltin (159*) were prepared in the usual way by a Grignardsynthesis involving methyltin chlorides and p-halogenophenylmagnesium halide. p-Chloro-phenyldimethyltin chloride (160*) was obtained in low yield from dimethyltin dichloride andp- chlorophenylmagnesium chloride:

49

AFM L-TR-65 -192

~U) CDCD

C.,- 00- -

to 0O m 0 e f

t- .-D to CD C

aJ 0 o 0 V) t- m Ca - CD Lj 4 r-f r4 -4 C13

(D r4 r-4 .0I 14 r0

1. 14 -4L~0 4, 0 CD C) . OlC

.4.) .J~O ~ ~ 0

W ... I I I I x

N) C Lfq cqI- L~ f

0 ccC~ CD 0- t-

o4 m, 00

H -D

I qLq>U

_ (D

UC)

CC

C11 0e eqcl Cd00 b a

wC C9 C4)1

CD m q e 0 s~C)4 Cl 0.) co .cd

_ _ _ _ _ _ _ _ __9_ q

.4t:

eq eq q 0 eqeq cli ,.4

eq ID

0~C CDCD eC.) C.) C.1

0.) C.)

In to mdti.1-c~ I4 14 r-4 :.C:Q

a) C.) 950

AFML-TR-65-192

Me.SnCI 2 + C90 Ce.nO (LVII1)

(160*)

A redistribution reaction involving dimethyltin dichloride and bis (p- chlorophenyl)dimethyltingave better results:

Me2SnCl 2 Sn('•Cl)2 - 2 ClMe.Sn'OCl (LVIII)

The model reaction of trimethyltin chloride and p-chlorophenyltrimethyltin with sodiumin refluxing toluene proceeded very sluggishly, bis(p-trimethyltin)benzene (161*) was ob-tained in only 40 percent yield. The synthesis of the dimer bis(p-trimethyltinphenyl)di-methyltin (162*) was attempted by each of the following routes:

2Me SnCI + MeS(C) No in Me Sn( /')SnMe ) Me i LIX)3 Me2 Sn( 2 toluene 3 22

S~Na in

Me2 SnCI2 + 2 Me3 Sn C toluene id. (LX)

Me2 SnCI 2 + 2 Me3 Sn -OMgCI THF id. (LXI)

In each case the reaction product consisted of a mixture from which the wanted productcould be isolated in pure form in a yield of only 5-10 percent. Peculiarly enough, bis(-trimethyltin)benzene (161) was isolated in yields up to 40 percent.

With a view to the unfavorable results obtained with the monomeric compounds, it is notsurprising that our attempts to obtain p-phenylenetin polymers have remained unsuccessful.Experiments, according to each of the following equations, were carried out:

Me2SnCI Cl No iCn [-SnMeNa-] (LXII)M 2 + toluene [ -S n

Me SnC + CIC Mg in id. (LXIII)2 2THF

Ce Na in - id. (LXIV)CIMe 2 Sn ~ .CI tlee-toluene

51

AFML-TR-65-192

Most of the starting material was recovered from Reaction LXII. Reaction LXIII yielded onlyoily products with a wide boiling range. Similarly, the self-condensation of p-chlorophenyl-dimethyltin chloride afforded a liquid, the analysis of which was not in accordance with theexpected product.

In view of these unfavorable results we have discontinued this line of work.

E. Investigation of Other Condensing Agents

In the previous sections the synthesis has been described of poly-p-phenylenesilanes and-germanes by means of Wurtz-type poly-condensation reactions of appropriate combina-tions of bifunctional p-chlorophenyl and chlorosilanes or -germanes with sodium sand intoluene as the condensing agent. However, under these conditions only low-molecular weightpolymers were obtained. Therefore we have looked into the possibility of obtaining thesestructures by means of other condensing agents (compare also Section V).

Poly- condensation of dichlorodimethylsilane with bis(Lp-chlorophenyl)dimethylsilane (127)or homopoly-condensation of the latter using a sodium dispersion in paraffin oil or a liquidsodium potassium alloy did not yield the expected products:

No in paraffinMe.SCI2 I Cl SiMeG CI oil or '/I [-Sime

Me SiCI + CI ~ Na/K alloy 2

(LXV)

0l Se. C No in paraffin oil °r,, iOS -oCSCl Na/K alloy /" Me2

(LXVI)

All products obtained after fractionation consisted of low-melting fractions, soluble in aro-matic solvents, and an extremely high-melting fraction, insoluble in any type of solvent tried.The solubilitq and the melting points of the polymer fractions suggest that initially low-molecular weight (linear) chains are formed, which on further condensation are cross-linked. The infrared spectra of the infusible polymer samples obtained in the homopoly-condensation reactions show an absorption at the frequency characteristic of the Si-O-Sivibration. This fact, together with the high silicon content of these fractions, suggeststhat silicon-carbon bonds are broken both by sodium and by sodium-potassium alloy in thehomopoly- condensation reaction.

Very recently Wurtz-type condensations, using a sodium-naphthalene solution in tetra-hydrofuran as the condensing agent, have been described (Reference 67).

In order to investigate the applicability of this homogeneous system to the preparation ofp-phenylenesilanes sodium-naphthalene was reacted with triphenylbromosilane and p-chloro-lhenyltriphenylsilane (128*) in THF:

S~Na/Na pht.

Ph Si CI+ BrSiPh3 THF - Ph Si SiPh (LXVII)

52

AFML-TR-65-192

Carrying out the reaction at about 60°C more than the calculated amount of sodium was con-sumed. It is likely that phenyl-silicon bonds are cleaved at this temperature by the reactivesodium complex.

To avoid this side-reaction the reaction temperature was lowered to 00C. However, p-bis-(triphenylsilyl)benzene was obtained now in only 17 percent yield, whereas the sdartingmaterial Ph 3 SiBr was recovered in only 40 percent yield.

These results indicated that these systems most probably are not suitable for the prep-aration of high molecular weight poly-p-phenylenesilanes.

The possibility of preparing poly-_p-phenylenesilanes by means of a Friedel-Crafts re-action has been studied also. To this purpose chlorodimethylphenylsilane (163*) was heatedwith a few Friedel-Crafts catalysts:

n (SiMe 2 CI 2 C cat. [-SiMe 2 -In + n HCI (LXVllI)

After heating the compound with 1 percent of catalyst (BF 3 .Et 2O, SbC13 or FeC13) at

200o-2300 for 14 hrs., the starting material was recovered in 91-93 percent yield. Heatingthe compound with 1 percent of A1C1 3 at 2300 for 13 hrs. yielded 84 percent of the starting

material, together with a few percent of low-boiling products.

Heating 10 g (0.06 mole) of PhMe2SiC1 with 1 g (0.0075 mole) of A1C13 at 140° for 13 hrs.

yielded a mixture of compounds in which the starting material was no longer present. Thefollowing compounds were identified: Me 3 SiCl (0.02 mole), Ph4 Si (0.004 mole), Ph3SiOH

(from Ph3 SiC1, 0.01 mole) and an oil, obviously a siloxane:

PhMe2SiCI AICI- Me.SiCI + Ph SiCI + Ph4Si + (LXIX)2 1400~~ 3 4S+

Heating 10 g of PhMe 2 SiCl with 1 g of FeC13 at 2100 for 10 hrs. yielded a low-boiling

fraction (Me 3 SiC1, yield about 8%) and a high-boiling one, obviously impure starting material

(yield about 80%).

A similar study with p-chlorophenyldimethylsilane (164*) has been carried out. After heatingthis compound with 10 plrcent of FeC13 at 200' for 12 hrs., the starting material was recoveredin about 70 percent yield.

Heating 8 g (0.044 mole) of the hydride with 0.4 g (0.003 mole) of A1C1 3 at 1500 for 8 hrs.,

yielded a volatile compound (obviously dimethylsilane, 0.012 mole) and 7.0 g of a mixtureof compounds, in which the starting material was no longer present. Infrared spectroscopyand elementary analysis point to the presence of compounds like tris-(p-chlorophenyl)-methylsilane and tetrakis(p-chlorophenyl)silane. Obviously the silicon hydride, just likethe chloride, disproportionates under the influence of aluminium chloride:

53

AFML-TR-65-192

[- SiMe2-]n + n HCI (LXXa)

S~1500n CI f&Si2H 2AInI

SMe2SiH2 + (CIC 6 H4 )3 SiMe +

+ (CIC6 H4)4Si + ...... (LXXb)

From these experiments it was concluded that Friedel-Crafts reactions under these cir-cumstances are not suitable for polymer formation.

54

AFML- TR- 65-192

SECTION V

SYNTHESIS AND DEGRADATION OF GROUP IV ORGANOMETALLIC

DERIVATIVES OF ORGANIC SALTSA. Discussion

Efforts to synthesize poly-p-phenylenesilanes and -germanes, polymers of a type thatexhibits a considerable thermal stability (750°-950°F), have been described in the precedingchapter. However, the Wurtz-type condensation used for their preparation does not allowthe attainment of high-molecular weight products. No other routes leading directly to polymersof this type have been mentioned in the literature and we have been unable to devise anyuseful suggestion along this line.

Lack of appropriate polymerization methods is a general problem in the preparation ofreally thermostable polymers. Although the synthesis of several novel low-molecular(organo)metallic compounds of promising thermal stability has been reported in the litera-ture, suitable techniques for carrying out these reactions on a high-polymeric level arenot available. A solution of this problem may be a two-step procedure, in which first a high-molecular weight pre-polymer is prepared by a usual technique and subsequently this pre-polymer is transformed by a, preferably simple, procedure into the final, inherently in-soluble and infusible, thermostable polymer.

The solid state polymerization of alkylenediamine-thiocarbamic acid salts to high-molecularweight polyureas (Reference 68), under generation of hydrogen sulphide, is one of the earliestexamples of this type of polymerization:

n H2 N-R-NH2 + n COS - n NH3-R-NH-C-S

0

-NH-R-NH n (LXXI)

A potential application of this principle to the preparation of IVth group organometallicpolymers containing the p-phenylene group, would seem to be a combination of a poly-condensation process and a decarboxylation or similar reaction in the solid state, e.g.:

ZZ

IV It CY 2 n HXn R2MIx 2 + n HYC CYH

/__ / \!R Zz -I Av

A [nQZ -] (LXXII)

R n n

Y = OS Z OS

55

AFML-TR-65-192

B. Synthesis and Attempted "Decarboxylation" of Group IV Organometallic

Cyanoacetates, Benzoates, Thiobenzoates, and Dithiobenzoates

The decarboxylation and related reactions of Group IV organometallic derivatives oforganic salts, which may produce aryl- Group IV metal bonds, has been studied on themonomeric level. To this purpose a number of appropriate organosilicon and -tin carboxy-lates, thiobenzoates and dithiobenzoates were synthesized.

pý-Phenylene-bis(diphenylsilylbenzoate) (165*) was obtained by the reaction of p-bis-(cElorodiphenylsilyl)benzene (54) with benzoic acid in the presence of pyridine:

CIPh 2 Si -SiPh 2 CI + 2 PhCOOH pyridine e

PhCO2 SiPh 2 .OSiPh2 02CPh (LXXIII)

(165 *)

Triphenylsilyl benzoate (166*) was similarly prepared. However, all attempts to de-carboxylate these compounds at various temperatures (up to 300'C) and pressures were un-successful. No weight loss was observed and the infrared spectra remained unchanged:

Ph SiO2 CPhI-/ '-" Ph4 Si + CO (LXXIV)

Organotin cyanoacetates are readily decarboxylated to cyanomethyltin compounds (Ref-erence 69):

R.SnOCCH CN - N RsSnCH2CN + C (LXXV)32 2 3 2

The positive result with the organotin cyanoacetate suggested a corresponding experimentwith a silyl cyanoacetate. Triphenylsilyl cyanoacetate (167*), prepared by the reaction ofbromotriphenylsilane with potassium cyanoacetate, was heated at 200°C/16 mm for severalhours. Again, no decarboxylation was detected. Apparently the -SiO 2C- structure is ther-mally quite stable.

Our attention was then directed towards a similar study of the corresponding thioben-zoates and dithiobenzoates. Triphenylsilyl thiobenzoate (168*) was prepared by the re-action of potassium thiobenzoate with bromotriphenylsilane in refluxing toluene:

0 0II II

Ph 3SiBr + PhCSK - - Ph3 SiSCPh (LXXVI)

( 168

56

AFML--TR-65-192

The high boiling point of this compound (about 2000/0.02 mm) without any decomposition

suggested a considerable thermal stability. Further attempts to eliminate carbon oxysulphideat elevated temperatures were unsuccessful.

All attempts to isolate pure triphenylsilyl dithiobenzoate from potassium dithiobenzoateand triphenylbromosilane have failed because of its extreme hydrolytic susceptibility re-sulting in the formation of triphenylsilanol. The organotin analogues, triphenyltin thioben-zoate (169*) and dithiobenzoate (170*), were readily prepared by similar procedures and arehydrolytically much more stable. Triphenyltin thiobenzoate did not change upon heating at220°C for prolonged periods. Attempts to eliminate carbon disulphide from triphenyltindithiobenzoate at elevated temperatures resulted in a complex mixture of solid and liquidreaction products which could not be separated. Among these products triphenyltin thio-phenolate (171*), independently prepared from triphenyltin hydride and thiophenol, did notseem to be present.

The negative results obtained in this study make successful reactions on a polymeric levelhighly improbable.

C. Synthesis and Desulphination of Organotin Sulphinates

In the previous section the synthesis of Group IV organometallic benzoates, thiobenzoates,and dithiobenzoates has been described. Attempts to eliminate carbon dioxide, carbon oxy-sulphide or carbon disulphide at various temperatures and pressures were unsuccessful.It has been reported in the literature (Reference 70) that arylsulphinic acids react withmercuric chloride or acetate to yield arylmercuric salts. Therefore it seemed worth ourwhile to investigate similar reactions involving arylsulphinates of Group IV elements. Tothis purpose a few organotin arylsulphinates were prepared and their behavior at elevatedtemperatures was studied.

Triphenyltin benzenesulphinate (172*) was prepared by an interfacial condensation of tri-phenyltin chloride (in ether) with sodium benzenesulphinate (in water):

Ph 3 SnCI + NoO 2 SPh P Ph3 SnO2 SPh + NoCI (LXXVII)

(172")

Diphenyltin bis(benzene sulphinate) (173*) was obtained in the same way. An attempt toprepare diphenylchlorotin benzenesulphinate by a similar condensation reaction yielded a 1:1complex of diphenylchlorotin benzenesulphinate and diphenyltin oxide (174*):

2 Ph 2SnCI2 + NoO 2SPh + H 20 -a- Ph 2Sn(CI)O 2Ph. Ph 2SnO + NoCI + 2 HCI (LXXVIII)

(174 )Triphenyltin p-tolylsulphinate (175*) and triphenyltinp-acetylaminobenzenesulphinate (176*)

were obtained is described above. Triphenyltin p-bro-mobenzenesulphinate (177*) was pre-pared by the following sequence of reactions:

PCi .) No 2 SO3

BrS o 5 Br .~ so C1 NoOHSO 2 2) HCI

IN) NoOH

Br SO 2 H 2) PhSnCI BS0SnPh3 (LXXIX)

(177*)

57

AFML-TR-65-192

Upon heating triphenyltin p-tolylsulphinate at about 2350/0.2 mm during 25 minutes a gas

was evolved and the solid melted, yielding after cooling a mixture of compounds. Purecompounds could not be isolated, but the fractions obtained upon recrystallization obviouslyconsist of triphenyl-p-tolyltin and tetraphenyltin. The infrared spectra of these mixtures,

in particular the C-H out-of-plane vibration of 1,4-disubstituted benzenes at about 800 cm-1,showed that the decomposition reaction under these conditions yielded about 30 percent oftriphenyl-p-tolyltin and 10 percent of tetraphenyltin. Obviously redistribution of the tri-phenyltin group had also played a part:

APh3 SnO2 SR - - Ph 3 SnR + SO2 + Ph4 Sn + ...... (LXXX)

Further information about the decomposition reaction was obtained from a series of ex-periments in each of which the reaction products were isolated and the sulphur dioxideliberated was titrated. To this purpose triphenyltin benzenesulphinate was decomposed byheating during 20 mrin. at about 2250 at several pressures. The gaseous products weretrapped in long tubes cooled by liquid air. The contents of the tubes were subsequently bubbledthrough a 2 N potassium hydroxide solution. The resulting solution was analyzed by titrationwith iodine and sodium thiosulphate. The results of these experiments are presented inTable 21.

From this table can be derived that:

a. Tetraphenyltin is formed by redistribution of the triphenyltin group in about25 percent yield, irrespective of the pressure.

b. Tetraphenyltin is formed by elimination of sulphur dioxide in yields varyingfrom about 10 percent at 200 mm to about 30 percent at very low pressures.

c. The part of the sulphinate that is not consumed in a. or b. decomposes intointo low-melting products.

Obviously, the present mode by which the reaction is accomplished tends to be not verysuitable for the formation of a phenyl-tin bond, unless catalysts are found that promote de-sulphination reaction and, at the same time, allow the temperature at which desulphinationoccurs to be reduced, thus suppressing the redistribution reaction.

Catalysts, that favor the elimination of sulphur dioxide from salts of arylsulphinic acids,have not been reported. Only the decomposition has been described (Reference 71) of a fewarylsulphinic acids to the corresponding benzenes by heating in solvents, preferably pyridine.

A few preliminary experiments along that line have been carried out. Triphenyltin benzene-sulphinate was heated with pyridine or quinoline. However, only small amounts of tetra-phenyltin were isolated. Similar negative results have been obtained using small amountsof copper, cupric oxide, or mercuric chloride as a catalyst. Copper seems to enhance theformation of tetraphenyltin by redistribution.

58

AFML-TR-65-192

'1li-iC

0. CO -4 4 - 1i60

eq c q q e

u- c- o L-- 0q m 00

m LO Id4 t to 00

oo

0) to 101 C

I oo CD ) 0- i-o LOCd q -0 r4I v.m m

Ll

a) m G) CD C

ce m

cl M - ( to LO to Ne-cON 0~ O 0 D t

_0 1- 14 v.04 uj1

'-4 4

U' MC

0 aca) Co 0 0

cq CO Co C

E -- 0 -

CL- t to La r o

C= ob

Eo 0E I

L0

59

AFML-TR-65-192

SECTION VI

AN APPROACH TO THE SYNTHESIS OF A QUASI-AROMATIC SILA-AND STANNATROPYLIUM ION

A. Discussion

As a sideline of our investigations efforts have been made towards the preparation of un-saturated Group IV organometallic heterocycles, in particular Group IV metallo -2,4,6-cycloheptatriene derivatives. These compounds are of interest because in principle, theymay aromatize to form a tropylium-ion structure, e.g.:

R

SM- I-R X A + RX (LXXXI)

A study of these compounds and in particular of their aromatized derivatives, althoughmainly of interest from a theoretical point of view, might be of value for Group IV organo-metallic polymer chemistry too.

The following reaction routes were selected for the synthesis of these seven-memberedunsaturated Group IV organometallic heterocycles:

X 0 P. Ph -O)CH M IVR -CH P ) pPh X o PhLi3 2 2 2 3or NoNH 2

- PhP=CH-MIVR2_CH- Ph3 H--- h 3CM-R +=.c~ L• •L ••,,• • 2Ph 3 P=O

6(LXXX II)

61

A FM L-TR- 65-192

(LXXXIII)

/ \ MIVI

R R

R MIV 2

M IV x4

m IV(LXXX IV)

OH

HCýC-CH -CH(OH)-CE--CH + R SnH -H-00 (LX XXV)

2 2 2 CSn ~

R R R R

C - CH AplR

II~I11II~CH + RSH. S~ U II nN. (LXXXVI)

62

AFML-TR-65-192

B. Attempted Syntheses of Group IV Metal-Containing Heterocycles via the WittigReaction or via Condensation Reactions with o,o" -Terphenylenedilithium

Recently Wittig and coworkers (Reference 72) reported the synthesis of unsaturated seven-and eight-membered cyclic compounds via the Wittig reaction; 1,2-benzo-1,3,5-cyclohep-tatriene, 1,2-benzo-1,3,6-cycloheptatriene, and 1,2-benzo-1,3,7-cyclooctatriene could beprepared by this method. These successful syntheses induced us to investigate the applica-bility of this type of reaction to the preparation of unsaturated metal-containing hetero-

cycles (LXXXII, MIV = Si, Ge, Sn; R = Me, Ph). To this purpose some experiments have beencarried out, directed to the synthesis of halogenomethyl- substituted organosilicon and organotincompounds and their triphenylphosphonium derivatives.

Bis(iodomethyl)dimethylsilane (178*) was obtained by the reaction of bis(chloromethyl)-dimethylsilane with sodium iodide in acetone. The triphenylphosphonium derivative of thiscompound (179*) was easily prepared by heating with triphenylphosphine:

2 Ph 3 P + (ICH 2 )2 SiMe 2 1•qPh 3 PE) -CH2-SiMe 2 -CH2 - PC) Ph3 .I

(178*) (179ý*) (LXXXVI I)

To obtain similar organotin compounds bis(bromoethyl)tin dibromide (180*) was preparedfrom tin tetrabromide and diazomethane according to published methods (References 73,74). Phenylation of this compound with two equivalents of phenylmagnesium bromide orphenyllithium afforded bis(bromoethyl)phenyltin bromide (181*) as the main product. Allattempts to introduce a second phenyl group in this molecule were without success. A sim-ilar situation had been found (References 75, 76) in the synthesis of aryl-substituted halo-methyltin compounds from aryltin halides and diazomethane. Only chloromethyldiphenyltinchloride had been obtained (Reference 75) from the reaction of diphenyltin dichloride withan excess of diazomethane. Introduction of a second methylene radical seems to be im-possible. Similarly, triphenyltin chloride does not react at all with diazomethane (Ref-erences 75, 76).

The possibility of obtaining halogenomethyltin compounds via organolithium compoundswas studied also. To obtain chloromethyltriphenyltin triphenyltinlithium, prepared by aprocedure described by Tamborski et al. (Reference 77), was reacted with an equimolecularamount of bromochloromethane. Interaction of the reactants at room temperature yieldedconsiderable amounts of hexaphenylditin and methylene-bis(triphenyltin), but no chloro-methyltriphenyltin was found. Carrying out the reaction at low temperatures (-650 C) againyielded considerable amounts of hexaphenylditin together with a low-melting solid, fromwhich, however, after treatment with sodium iodide in acetone, triphenyltin iodide was ob-tained. Obviously halogen-metal interchange plays an important part in this type of re-action, yielding triphenyltinhalide (isolated as the iodide), which partly reacts with tri-phenyltinlithium affording hexaphenylditin. The formation of methylene-bis(triphenyltin)may be explained by several reaction routes. Cleavage of this compound by iodine yieldeddiphenyl(triphenylstannyl methyl)tin iodide and phenyliodide instead of the product aimed atviz. iodomethyltriphenyltin.

A few experiments were carried out directed to the preparation of the seven-memberedsilicon-containing heterocycle from the triphenylphosphonium derivative of bis(iodomethyl)-dimethylsilane and o-phthaldialdehyde according to Equation LXXXII. However, all effortsto isolate the heterocycle were in vain. Infrared spectra of the products obtained fromthe reaction mixture showed the presence of Si-O bonds.

63

AFML-TR-65-192

Very recently Gilman and Tomasi (Reference 78) obtained similar results viz.:

R3SiCH-PPhp3 P--h2C- R SiO) + Ph2 C=CH-P) Ph3

SR3 SiOH + Ph2 C=C=PPh 3 Ph 2C-C-CPh2 + Ph3 P=O

(LXXXVIII)

We have looked also into the possibility of obtaining seven-membered tin-containing hetero-cycles from aryldilithium compounds and tin halides. To this purpose o,o"-terphenylene-dilithium, prepared from o-terphenylene-mercury-cyclic dimer (Reference 79), was broughtinto reaction with diphenyltindichloride. Although a reaction occurred, all attempts to isolatethe expected compound from the reaction mixture were without success. On the other handconsiderable amounts of o-triphenylene were found to be present. Obviously metal-halogeninterchange has occurred:

%Sn (LXXXIII)

2 Sn C 2 Ph Ph

Li-Clinterchange (LXXXIX)

64

AFML-TR-65-192

Because organohalogenosilanes show a lesser tendency towards metal-halogen exchange it isto be expected that similar condensation reactions involving silicon halides will result in theformation of the wanted heterocycles.

C. Synthesis of Linear and Cyclic Tin-Containing Compounds by Means of OrganotinHydride Addition Reactions

As outlined in Section I addition of organotin dihydrides to bifunctionally unsaturated com-pounds may yield tin-containing heterocycles, the formation of which is mainly governed bysteric factors. Therefore, the possibility of obtaining 1-stannacycloheptatriene-2,4,6 deriv-atives via organotin hydride addition reactions has been studied also.

In Section L C. the addition of organotin dihydrides to hexadiyne has been described, yielding,in addition to polymeric products, small amounts of 1-stannacycloheptadiene-2,6 derivatives.This induced us to investigate the reaction between organotin dihydrides and 1,5-hexadiyne-3-ol. It was to be expected that in addition to polymers also cyclic monomers would be formed,which could possibly be dehydrated to yield the wanted unsaturated heterocycles:

HC-C-CH2-CH(OH)-C- CH + R 2SnH2 No H OH

c -CH H H\

HC CH-o- [-CH=CH-CH 2 -CH(OH)-CH=CH-SnR 2 - I + 1 (XC)

HC N SnI-,"CHSn

R RH OH/c -c'H H\C

HC HI CH11 11 -2_.0_ (0 ,xc.HC sCH k n /

Sn Sn

R eR R/ \ R

In order to study the addition reaction of organotin hydrides with unsaturated compoundscontaining a hydroxyl function some model reactions were carried out. To this purposetriphenyl- and triethyltin hydride were brought into reaction with divinylcarbinol and divinyl-glycol respectively.

Upon reacting triphenyltin hydride with divinylcarbinol a tacky very viscous oil wasobtained. As appeared from analytical and infrared data addition had occurred in the usualway:

2 Ph3 SnH + CH 2 - CH-CH(OH)-CH-CH2 - Ph3 Sn-CH2 -CH 2 ._CH(OH)-CH2 -CH_2 -SnPh 3

(183*) (XC 1I)

65

AFML-TR-65-192

Reacting triphenyltin hydride with divinylglycol did not yield the expected 2:1 adduct. Sim-ilar experiments with triethyltin hydride and the unsaturated alcohols did not yield pureproducts though addition had occurred.

These rather disappointing results made a successful synthesis of the seven-memberedheterocycle according to Equation XC highly improbable. In fact the pure cyclic monomerwas not isolated from reaction mixtures obtained from hexadiyne-3-ol and diethyl- or di-phenyltin dihydride. Only low-melting polymeric materials were obtained.

1,5-Hexadiyne-3-ol (184*) was obtained by the reaction of propargylaldehyde with allenyl-magnesium chloride, according to Sondheimer et al. (Reference 80). The addition reactionswere carried out as described previously.

A tin hydride addition reaction which, in view of the nature and the position of the un-saturated groups, may lead directly to the formation of the unsaturated seven-memberedheterocycle, is the reaction of organotin dihydrides with o-diethynylbenzene. Therefore thereaction of organotin hydrides with this compound was investigated. Addition reactions withthe corresponding dienic compound, o-divinylbenzene, were included in this study.

Some model experiments were carried out with organotin monohydrides and the unsaturatedcompounds. Addition of triphenyltin hydride to o-divinyl- or o-diethynylbenzene affordedthe 2:1 adducts in satisfactory yield (see also Table 22);

CH =CH2 OH -CH - Sn Ph3

+ 2 Ph 3 SnH O (XCIII)

CH =CH2 • CH 2 -CH 2 -Sn Ph 3

(185)

C=CH OH -CH-SnPh

+ 2 Ph SnH - (XCIV)

O C--CH CH CH-SnPh3

(186)

Subsequently, organotin dihydrides were brought into reaction with o-divinylbenzene. Fromthe reaction of diphenyltin dihydride with the unsaturated compound, in addition to a polymer,a cyclic monomer and a cyclic dimer were obtained. Other products were not isolated:

+ R2SnH2b SnCI R +

Sa CH=CH2 0

187, R = Ph

188, R Et

66

AFML-TR-65-192

cq)

C; m2 020 0cn r-q eq cq c

_C; 02 02 02 020(D 4-i

m 14 00 1-4 eq mc;m l

U-.4 .-I r.- eqc - -4C -c; t: 0a m m a ) m 0; 0q

N4 .- 4 ,- - - e q14 eq ol 14 0

_) 0C

f- -

020 .,

E4 M a

10 02 ~~0 w 0 2 ~ 0

J0~ 0 0 0 0 0 0 0 0 LO 0

01 r-0 - 0

IqR- -:0

11 0 00 00 '0 '.

0 0 r

cqI 0- 0 ~ - 2 0 0 2 ~ I 0

ol >~ 02

r- eq m >C)O D moCý 0 002 C, m 4 eqI4 ý ' 0

m t-. I I~ .44 e) C1 It Iý L- 0

02

-O Cp 114 0 O

r-I~~~~~~- r- .c q t C)-4 q0

0-e0 2 0- '14 ,-I)U 0ME 002 02 to 00 00 040 00 C)

04cc t- I q coq -I c-C I > qP

o$4 .-- ZUJ~~~~~~~~e bb00 0 0 0 C - t q U - U

5 - CO U) C-9 r-4 C- d- C - ) e 4 C- U O C

'4- 9 lC O 0 oME .44 U) 0 t eq r- C O a! . :' - 0!

(1) 00 0- m 0 C O 0 eq CO CO 0 q c :p V

m - Q- 0 CO C- 0 L-4 Co4 eq 0 ) L 0 UM (

Coo " M C M' eq) L- aD CqO

'-D (D)

C') 0q I.. eq eq C) q '4 C 4 C- C 4 ~-J COi eq 0 0 4 0 0 C 0 U 0 00 00

eqi OD U) 02 0l: U) 02 " 00 O CD 4eqCO I r- r- O

0 . 02

ZE CeO Cl) cq r- Cl) 14 C) V,eq CO eq eqi .44 eqi eq4 044 CO CO CO4 CO4 ?-1 N

q44 01 eq eq Q44 r-I r-I r-I mO "O 0 b

0 0 0 0 0 0 -. -~

L ) O CD - 00 02 0 .-I eq ce) "4 U CD L- 00 02 0D0O oo 00 OD CO 02 02 02 02 02 02 02 02 02 02 0

-4 -4 -4 -4 1-4 r-4 V-4 -4 -4 r-4 -4- -4 V-1 r4 r eq

67

AFML--TR-65-192

R RR\ /R

SnR

SCH 2-CH2 -Sn-+ + R' (XCV)

CH2-CH-

Sn

R R

190, R = Ph

189, R Ph 191, R = Et

A similar experiment involving diethyltin dihydride yielded only the cyclic monomer and apolymer. So far the cyclic dimer, most probably also present in the reaction mixture, couldnot be isolated by the usual techniques.

The successful results obtained in the above described experiments led us to carry outunder similar conditions (gentle heating in inert solvents) addition reactions involving organotindihydrides and Q-diethynylbenzene. However, from the reaction of diphenyltin dihydride witho-diethynylbenzene only the fourteen-membered heterocycle and a polymer could be obtained.All efforts to isolate the cyclic monomer were in vain.

As has been mentioned in Section Ithe addition of organotin hydrides to acetylenic bonds mayproduce trans-and cis-products dependent on the steric course of the addition and on anysubsequent isomerization. The addition of triphenyltin hydride to phenylacetylene at roomtemperature exclusively produced the trans-product (either occurrence of cis-addition orisomerization of the cis-product), the addition of triphenyltin hydride to propargyl alcoholobviously furnished both isomers (Reference 34). It seems therefore that, when voluminousgroups are attached to both reactants (e.g., phenyl groups), either trans-addition (formationof cis-products) is hindered by steric factors, or the initially formed cis-product readilyisomerizes under these conditions. So, the formation of the cyclic monomer from diphenyltindihydride and' o-diethynylbenzene under these circumstances becomes highly improbable.

However, very recently it has been reported (Reference 81) that upon the addition oftriphenyltin hydride to phenylacetylene at -700, 91 percent of the adduct formed (no yieldspecified) has the cis-configuration (occurrence of trans-addition). The cis-product at roomtemperature readily isomerizes to the trans-product. Similarly, by carrying out the reactionof diphenyltin dihydride and o-diethynylbenzene at -70°, initial trans-addition might stericallymake possible addition of the second Sn-H group to the second ethynyl group with formationof the cyclic monomer. Subsequent isomerization, if at all possible, would be of no concern.

In order to test this possibility diphenyltin dihydride was reacted with o-diethynylbenzeneat -70°C. However, again the cyclic monomer couldnot be isolated from the reaction mixture,although the polymers obtained in these low-temperature experiments showed an increasedamount of cis-bonds.

Trimethyltin hydride when added to phenylacetylene at 400 afforded 58 percent of the cis-adduct (30% conversion in 24 hrs see Reference 81). Because of the more favorable cis-trans

68

AFML-TR-65-192

ratio at higher temperatures of trimethyltin hydride-adducts, similar experiments were

carried out with dimethyl-, ethylphenyl-, and diethyltin dihydride respectively and o-diethynyl-benzene.

The reaction of dimethyl- and diethyltin dihydride with o-diethynylbenzene afforded, inaddition to polymeric products, small amounts of the cyclic monomers, which were purifiedby distillation at reduced pressure. No attempts were made to isolate the cyclic dimers fromthe reaction mixtures, though they may be present as well.

From the reaction mixture obtained from ethylphenyltin dihydride and the diynic compounda high-melting crystalline product (cyclic dimer) and a low-melting product were isolated.The low-melting product was separated into a high and a low molecular weight fraction. Thelatter fraction consisted of almost pure monomer as appeared from molecular weight de-terminations and degradation with iodine (Section VI.D).

+ RR'SnH2 I IR

+C--CH C •R

192, R = R' = Me193, R = R' = Et194, R = Et, R' Ph

SnR

CH =CH-Sn -

+ R (XCVI)

CY CH "-CH- /n

Sn 197, R = R' = Me

R R 198, R = R' = Et199, R = Et, R' = Ph

195, R = Et, R# = Ph 200, R= R' = Ph196, R = R' Ph

Some data on the oligomeric and polymeric products obtained in these addition reactions(XCIII-XCVI), the identities of which were established by infrared spectroscopy, molecularweight determinations, vapor-phase chromatography, and elementary analysis, are collected

in Table 22. As can be seen from this table at least one absorption in the 780 cm-1 regionseems to be characteristic of the seven-membered heterocycles. A similar band has beenobserved in the infrared spectra of the 1-stannacycloheptadiene-2,6 derivatives described inSection I.C, but in the infrared spectra of the corresponding polymers only a very weak band

is observed at about 800 cm- 1 . The band at 780 cm-1 may be skeletal vibration of the seven-membered tin-containing heterocycle.

The addition reactions were carried out as described previously. Ethylphenyltin dihydride(201*), not described before, was obtained in very low yield via the reaction sequence:

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AFML-TR-65-192

SnCl 4PhSnCI3 + 3 EtMgBr - PhSnEt3 - - Et SnCI2 + EtPhSnCI -2 --

LiWH 4 Et2 SnH2 + EtPhSnH2 (XCVII)

(201 i)

Cleavage of two phenyl groups from ethyltriphenyltin by iodine and reduction of the resultingiodide gave better results:

Ph SnCI + EtMgBr . Ph3 SnEt 12 EtPhSnI 2 LAIH 4 EtPhSnH 2

(201*) (XCVIII)

o- Divinylbenzene (202*) was synthesized from o-oxylene, via o-di(bromomethyl)benzene,Qo-di(ethoxycarbonylmethyl)benzene and p- di (2-hydroxyethyl)benzene according to publishedmethods (References 82, 83). o-Diethynylbenzene (203*) was obtained by bromination of o-divinylbenzene, followed by dehydrobromination of the tetrabromo product (References 84, 85):

H H2

CHCH2 Br - CBr

+ 2 Br -2 t-BuOK[H H2-CH-CH2 CBr _CBr

SC ---- CH

ECH (XCIX)

(203*)

D. Degradation of Stannacycloheptatriene Derivatives by Iodine

As has been outlined before our interest was focused on stannacycleheptatriene-2,4,6derivatives with a positive charge on the tin atom, because such a system may have a moreor less aromatic character. To this purpose 3,3-dimethyl-, 3,3-diethyl-, and 3-ethyl-3-phenyl-3-benzostannepin were reacted with iodine using toluene, benzene, chloroform, or ether asa solvent. However, consumption of one equivalent of iodine did not yield the expectedproducts. Instead of splitting off the aryl group or one of the alkyl groups attached to the tinatom, the seven-membered heterocycle was opened. A second equivalent of iodine reactedmuch slower; probably the first reaction is facilitated by a substantial strain in the heterocycle.

The course of these reactions was studied by means of GLC and IR spectroscopy. A semi-quantitative study was carried out by treating a benzenic solution of 3,3-diethyl-3-benzo-stannepin gradually with the theoretical amount of iodine dissolved in the same solvent. The

70

AFML-TR-65-192

solutions thus obtained were analyzed by GLC and IR spectroscopy. The data are collected inTable 23.

As may be derived from these data the heterocycle "'A" is opened during the addition of thefirst equivalent of iodine yielding product B. This product is converted by a second equivalentof iodine yielding products "C" and "D". During the consumption of the first equivalent ofiodine small amounts of product B are converted already into products C and D.

Sn-*, Sn R'

"A"ll "e"

I+ RR'Sn1?2 (C)

"11C D ID"

Very small amounts of products C and D were isolated. The identity of the latter, diethyltindiiodide, was confirmed by the gaschromatogram and infrared spectrum of a synthesizedsample.

Upon reacting 3,3-dimethyl-3-benzostannepin with iodine the heterocycle suffered ringfission in the same way, yielding ultimately dimethyltin diiodide (not isolated) and product"C" (GLC-characteristic). 3-Ethyl-3-phenyl-3-benzostannepin behaved similarly.

Product "C" was identified as o-bis- (/B- iodovinyl)benzene (204*), most probably the purecis-cis isomer. A similar degradation has been proposed by Freedman (Reference 86) for thereaction of 1,1-dimethyl-2,3,4, 5-tetraphenyl-1- stannacyclopentadiene with bromine.

In none of these cases product "B" was isolated in pure form, but attempts have been madeto establish the nature of the iodine atoms present in it. To this purpose a sample was isolatedby evaporation of th solvent from a reaction mixture of equivalent amounts of 3,3-diethyl-3-benzostannepin and iodine in benzene. Iodine analyses of this product indicate that alliodine is benzene. Iodine analyses of this product indicate that all iodine added is presentin the form of high-boiling compounds and that about 50 percent of the iodine added is attachedto tin. This fact, together with GLC and infrared data and the identification of products "C"and ' D" justify our opinion about the existence and structure of compound B.

As may be derived from the experiments described above introduction of an ionic Sn-Xbond in 1-stannacycloheptatriene-2,4,6 derivatives in this way is higly improbable.

In view of the interesting theoretical aspects implied we have planned to continue ourstudies in this field of Group IV organometallic chemistry. Some reaction routes which may

71

AFML-TR-65-192

C>

V4I 10 ,4 0( 0

C- D ~I 0

C-1 I= ~- O

m 40(

u-i

0. -' 0 0 00 0

- > C)

!c-

0j .-4 eq 0qm t

--

eq~ Oq - 0 0 0 D

C; C,

CD 0D 0a M

I 4 I

C> 0 t-0 -- i

00 0 0

00U

u_. Cp + +C+ D

14 C> .-4 ?-

0D 0o 00 0ct -! rý - 0

CD 0 D ; 72

AFML-TR-65-192

lead to the formation of the compounds aimed at and which presently are under investigationhave been described below:

R + M IV X , IV +RM X (CO

C CH R /R

SRMIVHx -IVIV (CII)

SCOCH

0 + RM H2 X Mx (CIII)

73

AFML-TR-65-192

SECTION Vii

INFRARED SPECTROSCOPY OF GROUP IV ORGANOMETALLIC COMPOUNDS

IN THE ROCKSALT REGIONIn the course of this study numerous infrared spectra of reaction mixtures and products

obtained have been recorded. Various low-molecular and polymeric Group IV organometalliccompounds have been characterized in this way. Moreover, infrared spectroscopy hasproved to be a useful tool in the determination of the progress of several reactions, inparticular, of tin hydride addition reactions.

Some infrared data are presented in Table 24, specifically, those characteristic of vinyl,p-styrenyl, phenyl, and p-phenylene derivatives of Group IV elements. Some of these ab-sorptions, although not dr-rectly originating from vibrations of the metal atoms themselves,show characteristic shifts to lower frequencies as the weight of the metal atom(s) in themolecule increases. For a detailed discussion of these bands the reader is referred topublished reports (References 21-29, 41, 42, 46, 87).

The infrared spectra were obtained u s i n g a Perkin-Elmer Infracord Model 137 Spectro-photometer. The potassium bromide pressed disk technique was used for all the solid samples(denoted by sld. in Table 24); however, the liquids (denoted by liq.) were recorded in0.010-0.025 mm cells with sodium chloride windows.

The synthesis of the greater part of the Group IV organometallic compounds compiled inTable 24 have been described in the preceding chapters. The p-phenylene derivatives, p-bis-(triphenylgermyl)benzene (205*), p-bis(triphenylstannyl)benzene (206*) and p-bis (tripluenyl-plumbyl)benzene (207*), the preparation of which has not been mentioned-n the precedingsections, were obtained by a conventional Grignard procedure from p-dibromobenzene andthe respective triphenyl Group IV metal halides.

75

AFML-TR-65-192

to CD wD 0C

C- 0 (Dcr, 0 0

co N 0o1 qr

00 :a

0 CO 00 CO) to C> tC -L 4m C - o

o ~ 1. l . 0 00 0 0 0ý 0 l 0 t - C.q- o 0 0 o t t 0 0 0 V -: V CO o l: q 1-1 1- -4 4. 1-4 5- eq- 4 4 r

En anoJ0d 10 0 D DD D C

to m' 00 M QI -qN 4 r 4 m l1 - - 4 r q 4 1 - 4 r4 1

0. C. C)ý0 0 ~

0

CO meo 0 0 0 0 0 o 0 q eq4 CCA t- tCO m0 10 to CO 44 j 0 V M m C~c I4 I4 I4 ,1 - II4~

0 ~ Cco CD1 -lC)0 C . 0C

.-. 1 I.-

5to CDC

0~ ~ 04 .P4 Cq COpqO C M C O CM e q ~ O M t

T0 10 10 10 1 LO ~ Cl t o C

o4 Q .co 0 .O0 t

5-4 - -- IV

aSq

5.46

AFML-TR-65-192

02000

0~ 0

0m 444.-

I- C CO 44 4-4 -

> 00 0d o

.0 Iq -q 00 L 0 1 1i 00

'4-; l v-4 r C 00

7 i, q ;-D CD CD a C

'-4 00 00 m4- m o L 4-qC14I 4 rI m m 0 0

go CD 0 0 Q4- m C m a

cq c -I 4 02 0 D 0o Q CD1-4 £ - -1 I *I 14 I

0-.

eq 0-I 0 1 1 c q c 0 00 0- 0 02 02 0 00

E-- C3 .- -q ,l q c - -1 ID oj (D C4 eq ,-4 eq ea ID C C O 0LU 14 -4 r-4 COI 1-1 02 01 CO 1- -1 eq eq ~ -4 ,-4 2 0 2 O C

00 0q ,- O00D 00 0 - rI t )C. C 0 0 2 0 0 2 0

cflal

11 > > >2 >2 > >2

CO C O C 2 Cm.4 C 0 q CO0Q CID

< ID ID C11 14 e q ,- O - 4 COl mO e - 2 0eqý eq eq eq .- 4 .-i 0 P4 - 0 0 2 0 0

L)~' u8 -'o CD8t t oC

> > > > -4 -4 02 02>

P, P, "I PI4 P41 P4 P 4 P 02

I '8- L-- - I o4 -'-. Cl 14 CD CD4 02CD 0 C

02 eq r~4 l 4' )4 -I 4 Q-V-4

e q I ~ I I t i l I7e

AFM L-TR-65--192

T 0

c 0 0H

00000

-H 0

0- P4 -'n

w a ;"I(0 0 0 0 r

>0 4 (D 00 00

0n CD 00(n 00'H-* 0 04 .U)p QU)1 a) a. .4* ~

o U)

0 (D

0 00ra0 .010 (2

C.) .0 42U) U

a. 0q c ) Oq coc o L0(

m) L - ac) L- I> a- U) to

.0

00 Za > : ) > > U) Uo ) >r > w) > > >;> 0

C1 r q - oo ir) 1t 00 m~ r-4 r-I 1-1 eqi ,-I CD ) oo r.V3 .-4 0 to to eq m) o) U) oo U) OD M) C) 4 0 0

z t)I) 0 > - Uc) t- t- I. L- L- t- t- t-

x0 0a) ) M) U) M) U) 03 M

:- eq) e4 q t:- co U)~ to 0) 4 t- a" GO , ooV3) U) 0D eq eq eq ,-4 0 C) Uy) (n m bID (0) 0D 0) U) U) U) U) U)a- E:- cD to U) 4

q

U)

a: U) U) U) U) U) MI m > a)

C o 0) 0) U) 0 c) t- t- m ) U0) 0) 0) U) U) U)O) U t- t:- L- L:-0

- U) a -7 U)4

eq -" cq ~ ~ r~Pm m 11Cl U) 0U)

-4 P4 d)

ý . - W, % g.eq cl s)U)rJC

0 4) rU U 0 U U U Uw to w to a a cD

0~~~~~~ En '' U ~a a a '~4 'cd o

U)eq ~P4 P, U)4P, P, p4 "az1I P, '041 PI PI 9 0)

2'- In

0 0 0 0 aq

78

AFML-TR-65-192

SECTION VIII

SUMMARY AND CONCLUSIONS

A great variety of novel Group IV organometallic polymers, having molecular weights up to150,000, have been prepared by means of poly-addition reactions involving organotin di-hydrides and difunctionally unsaturated reactants. Model reactions have been carried out withappropriate combinations of difunctional and monofunctional reactants, affording low-molecular addition products. The polymer-forming reactions studied were of the type:

n R.SnH2 + n H2 C-CHR'CH-CH2 - CH2 CH2 R'CH2CH 2

n R2 SnH2 + n HC=-CR' [- nCH2 CH-n]R nn R 2SnH 2+ n HC=CR'C--CH -.- [,fnCH=CHR'CH=CH]

2 n

The relation between the nature of the unsaturated reactant and the properties of theresulting polymer has been studied by extensive variation of the first. As another exampleof an organotin dihydride a p-phenylene-bis(diorganotin monohydride) has been used as well.

The polymers range in appearance from rubbery or thermoplastic solids to viscous oils.A low softening temperature (around 100°C) seems to be an inherent property of the solidlinear polymers as a consequence of the presence of the bulky organotin group in the polymermain chain.

The presence of aliphatic carbon-tin bonds and the inevitable presence of /-hydrogenatoms set inherent limitations to the thermal stability of these structures (upper limit foundin this investigation at about 575 0 F).

Another approach to the synthesis of Group IVorganometallic polymers, viz, polymerizationof organometal-substituted vinyl monomers, led to the preparation and polymerization ofa series of triphenyl- and trimethylmetal-substituted styrenes:

CH CH 2 -CH-CH 2 -

n -----4-huA-- :;I MIV = Si, Ge, Sn, Pb

MIV 3 RMIV R3

'79

AFML-TR-65-192

The thermal stability of this type of polymers is limited by the occurrence of depoly-merization at temperatures around 650 0F.

A brief investigation has been made of the reactions of bis-cyclopentadienyltitaniumdiacetate and dichloride with diphenyl- and triphenyl-substituted Group IV metal deriva-

tives with a view to the possibility of preparing polymers with a -TiCP 2 -O-M IVR 2-O frame-

work. High-molecular weight products with the proposed structure have not been obtained inthis way. Products of the monofunctional reaction of sodium triphenyl-silanolate with bis-cyclopentadienyltitanium dichloride have been isolated and identified.

In connection with the search for more thermostable structures the synthesis of polymericGroup IV organometallics containing p-phenylene linkages has been studied. Wurtz-typecondensation reactions involving appropriate combinations of p-chlorophenyl- and chloro-silanes or -germanes were applied for polymer formation:

IVV 11 Iv-M -CI + C -- NM

A series of well-defined oligomers as well as polymers having a degree of polymerizationof 10-30 resulted from this work. According to expectation the poly-p-phenylenesilanes showconsiderable thermal stability (weight loss starts at 750°-950'F). The results of thermo-gravimetric analyses indicate that thermal stability increases with increasing degree of poly-merization. However, here the problem of realizing high molecular weights was encountered,a universally limiting problem in the preparation of thermally stable polymers. So far, ithas delayed attaining polymers with useful physical and mechanical properties.

Another approach to the synthesis of the above-described type of polymers, viz. the elimi-nation of gaseous products from a high-molecular weight pre-polymer which may be obtainedin a preceding step using conventional poly-condensation techniques, led to the synthesis ofseveral Group IV metal model compounds, like benzoates, thiobenzoates, dithiobenzoates,and arylsulphinates. However, attempts at formation of Group IV metal-carbon bonds byelimination of carbon dioxide, carbon oxysulphide, and carbon disulphide have been un-successful. Desulphination of organotin arylsulphinates occurred to some extent. This maybe a useful route to the preparation of functionally substituted aromatic and aliphatic GroupIV organometallic compounds, provided suitable catalysts can be found.

The preparation of cyclic Group IV metal-containing heterocycles have been studied. Inparticular Group IV metallo-2,4,6-cycloheptatriene derivatives are of interest, because thesecompounds, in principle, may aromatize to form a tropylium- ion structure:

'e' x - x 2 1 ýe0 1-am-tV i M VR X-RX

I-. -_ .

R

80

AFML-TR-65-192

Of the several routes investigated, leading to the seven-membered Group IV metal-containingheterocycles, the addition reaction of dialkyl- or arylalkyltin dihydrides with o-diethynyl-benzene proved to be the most useful. In this way, in addition to other interesting cyclicoligomers and polymers, some 3,3-disubstituted-3-benzostannepins have been obtained:

RR'SnH2 + OPC --- CH /R

R 2 +aw( ) S + cyclic dimer

C CH+ polymer

However, all attempts to establish a positive charge on the tin atom in these 1-stanna-2,4,6- cycloheptatrienes so far have been in vain.

Infrared characteristics in the rocksalt region of the compounds prepared in this study havebeen presented. Some of these bands show considerable shifts to lower frequencies as theweight of metal atom(s) in the molecule increases.

81

AFML-TR-65-192

U,

_M C'ý c:

ccuq- D l cqI eq eq c

00 0 I

'cj4 Lf) I f

r- -I V-4

0

0E C4) 1-1. ~ .

,E 1tv LO f

r- t- I I-Jo I II LO)~ L)tz- ce) to

-j if) (0 14 1-4

00P4.

1-4 0I C1 w-4 0)

eq q C4 0 0 (

w- m- w 1 )

-4 -JI r- eqf L r4 m" 0C

'4>

0- C11eq 0

0 0 e 0

00

eqm CV) Wq CI~ Weq e

0w 0 0 0J 0- *

r -4 Cq If) (0 C>) 4 If) m)0 ~eNq eq m4 LO LoI) I) f f

82

AFML-TR-65-192

cq eqej q eq eq eq c

LU q Co -i C c .

o mO La io q V-4 eq m~NDj 0 t I I to1 I m~ 0 eq eq m I

r4 r4 10'~4 14 10 10 r4

1-4

eq to eq ~eq -4 1-4 C) 0 o 4

cf E eq 10 C> . eL. "I, to eq Q4 Ci S

-M- 10 r.-4 7- 1 4 1-4 1m I I I 1 00 00

C13 I AO 0 00 10 I Im MO mO -4 0 m~ Ce

onI r-i rq I- 00

0- 00 eq co cO) 00cm D 10 r41-

I I I 4i I I I00 1OA0 0 eqL eq r-4

-J q eq0 e4 0 q eq

eq eq eq Oeqq 00 0 -__ -4 "q 0 q0 m00

10 0 0 0 00 ~ 000 eq eqeq3 U- 10 00 z 0 -l 00 c q 00 eq 00 0 0

eq r-q eq q eq eqq 0 4 q eq m0 eq r- Co

Co Co w c q 10. eq r-4 i4 t- -4 c)CO -4 oo4 00 r-4 r-4 V-4 1-4 V4 1-4 r-4 to m~

eq

0 u

0 M0 0 00C

q 00(D ZD cq Cq qe 0

0 0q zqeq~c c 0 OqC

eq~ ~~~~ 0) e q eqe I a

0~ zqP,~~~~~e eq ) cqc q q

00C Iv L V4 C 00 0 CD 0 0 O - Oeamq o ooO 00 C 0 000 00r4 l" r

""0 10 104 004 00l 00 0 0 4 r4l r-4 r-4

83

AFML-TR-65-192

(C.0

eq m~ C13 0 q C4 q eq C11 eq 03 a

L0 ; Q Lf; C; Lf: cc; a, a,; a;-

CC

a, eq a,) * e45to toI 0 0

E CDei-II 0 i

m 10 eq 0 -

r- 00 I- I- I I

0l 0 00 CD e0- 0 14 0o

CD ~ e 04 0q ,:V

I -q40, a0 A I, t- 00o

14 eq eq m 0 )IrIq

a-,

0 a, q .1 - ' q eq0 rca H~ q vi C1 ca . r4

U) -4 eq n4 11 -I a, -q V-1 eqi eq 0N eo 00 0 -0 0 u -I 0 0 - uci0 to ý 0ý to v u m , 00 u'4 V

eq q t o r- r-I r- T- 0D eq) C11-1 = m' -4 m- -

00 co cD q 144 v 4 t :.N e 1.4 t- -4 r-4 eq eq oo CV0) V- m

a- 00Oq - eq eq~0 04 ue cq C 4 -

- H4

0e 0 0 0

_ 0 0 0 q c i , 0 0 v-4 eq 1> a- eq eq e eq q eq eqae

u P, co84

AFML-TR-65-192

4j~C.,

Go COun cq eq 00 CO

1-4 Lo -.4 m co to tv- vI ' t- 00 r-4 v-4 r-i v-4 '.

eq toq- to eqto1- 0Or -

T-4 r-4 v-i v-I V-4 r-4

eq eq CO Co 0

eq o- ; CCO Vo0 0 -4~E V-4 eq Ce) 'c' - q N-

E -4 V- - -4 eq 0 00I I I I vq C I I

to 1q eq r-4 0-J -4 eq mo mO COD C'1

r-I v-I r-I v-I 00 m C0

tom- q eq V-1 eq

0 r4I to eq v-4 tO

I -4 CoI I Vj tý, Iv- q vj r-4 eq LO

vUm -4 meq .4 ft-

eqo0 '0C .- 4o q C1 eq mO eq C qeq r-4 CO $. . q 0 eq 0tO r - -4 Qq V-4 nv- 0 0 zeq .. C) to C.) CocC. q eq C) C)o t

0 -I Co r. y4 0> eq Co v-I '. CO eq -1q -4 w- V-4 w w - v-Iý

m meV q C M: tO r-4qOD m- V-4 v-I Go '.4 eq co Go eq eq

CO

a)qUC.ceq

eeq

eqq eqcqO ea)p 0) e

Co CO eq r/ mo C o CV-4 i-I a) ) Cf) v-) a)) a)

0 ~ ) t. C - q Co CDto tLO tO tO tO t o t to tD CD to to

'. -I T-4 . - - - - - - - - -

85

AFML-TR-65-192

GO

IJ0J0 00V - t- t - t

-4Ll r- -

Eor

00C)0 C- 1 0

o 0o

0m mII 0NU3 02 (0 M U

W 4 11 i q 0-4 -4 c

Lo - 0 0 l - P

cq CD~ I C> Cý C 0 0O C11 tt) mO 04 cq C

-J CQ 0 q N cq C4C It. 0e "I 0

C)1

c'cq

C, mi L) 0

0 -J Ni cq1 P, i)C1Cs4

u u' U1 A- m pq 0 ci) CI 3 cl)

Cq u. 0 0 0q 0q 0q 0q 114 a) - 0C~~~X C' ' 'I C qC C

11 L2 12C*4~4 04 0I m0~0

000 00 0 00 0 000000

pp

0 Al 0 0D

00 m 0 - q 0 v L o L D M ( - q C) "

to t - t . - - t - L - L- 0 0 0 0 0VI)C T-4 0- - - - - - - - - - - -

86C

AFML-TR-65192

~LS eq eq 0eq U

LA m eq m~ 00 00 0LU r- - - - - - -

0 0 00 00 0. 0

O -I m- I I

C) 0COO

- CO 0

100

IA CIDq )LOO 000

10 O CO mq ~

Loi~U LO c -) c

o -.1C

eq *. ci9 0

LO Oo04 o 0 00 0o 0 0O

0 UUU

a4-4

2mIC=O 0

C)L.

.. CO CO 0

- q eq 0 q 4 pqa

0 000

(5 ~~bD 1

P, P, P, Cd

r -I eq COD 10 CD -

Q 0 ) 0 Q 0 0 0D 0D__ _ q eq eq eq eq eq eq

87

AFML-TR-65-192

SECTION IX

REFERENCES

1-19. Administrative Reports No. 1 through No. 19 covering the period from March 1, 1959up to November 30, 1963 (Institute for Organic Chemistry, T.N.O., Utrecht, theNetherlands)

20. J. G. Noltes, paper presented at "WADC Materials Laboratory Conference on HighTemperature Polymer and Fluid Research," Dayton, Ohio, (May 26-28) 1959

21. J. G. Noltes, H. A. Budding, and G. J. M. van der Kerk, Rec.trav.chim. 79: 408 (1960)[Technical Note No. 1, "Preparation of Some p-Styrenyl-Substituted Derivatives ofGermanium, Tin, and Lead"]

22. J. G. Noltes, H. A. Budding, and G. J. M. van der Kerk, Rec.trav.chim. 79: 1076 (1960)[Technical Note No. 2, "Preparation and Polymerization of IVth Group OrganometallicDerivatives of Styrene and a-Methylstyrene"]

23. J. G. Noltes and G.J.M. van der Kerk, Rec.trav.chim. 80: 623 (1961) [ Technical NoteNo. 3, "Synthesis of some Hetero-Polymers Containing Germanium, Tin, and Leadin the Main Polymer Chain"]

24. J. G. Noltes and G. J. M. van der Kerk, Rec.trav.chim. 81: 41 (1962) [Technical NoteNo. 4, "Synthesis of Linear Organotin Polymers from Organotin Dihydrides andAcetylenic Compounds"]

25. J. G. Noltes and G. J. M. van der Kerk, Rec.trav.chim. 81: 39 (1962) [Technical NoteNo. 5, "Triphenylsiloxy Derivatives of Bis-Cyclo-pentadienyltitanium" ]

26. J. G. Noltes and G. J. M. van der Kerk, Rec.trav.chim. 81: 565 (1962) [Technical NoteNo. 6, "Synthesis of Organosilicon Compounds and Polymers Containing the p- PhenyleneGroup"]

27. A. J. Leusink, J. G. Noltes, H. A. Budding, and G. J. M. van der Kerk, Rec.trav.chim.,in the press [ Technical Note No. 7, "Linear Poly-addition Polymers Derived fromp-Phenylene-Bis- (Dimethyltin Hydride) and Diphenyltin Dihydride" I

28. A. J. Leusink J, G. Noltes, H. A. Budding, and G. J. M. van der Kerk, Rec.trav.chim.,in the press [Technical Note No. 8, "Synthesis of Organogermanium Compounds Con-taining the p-Phenylene Group. Some Infrared Characteristics of 2-Phenylene Deriv-atives of Silicon, Germanium, Tin, and Lead"]

29. A. J. Leusink, J. G. Noltes, H. A. Budding, and G. J. M. vander Kerk, to be published.

30. J. G. Noltes and G. J. M. van der Kerk, Chimia 16: 122 (1962) [Paper presented atthe "Symposium 'iber Polyadditionsprodukte und ihre praktische Anwendung," Zurich,October 1961 and read by G. M. Van der Wantj

31. J. G. Noltes and G. J. M. van der Kerk, paper presented at the "Conference on HighTemperature Polymer and Fluid Research," Dayton, Ohio, (May 8-11,1962)

32. G. J. M. van der Kerk, J. G. A. Luijten, and J. G. Noltes, Chemistry and Industry(1956) 352

89

AFML-TR- 65-192

REFERENCES (Continued)

33. G. J. M. van der Kerk, J. G. A. Luijten, and J. G. Noltes, J. Appl. Chem. 7: 356 (1957)

34. G. J. M. van der Kerk and J. G. Noltes, J. Appl. Chem. 9: 106 (1959)

35. J. G. Noltes and G. J. M. van der Kerk, Functionally Substituted Organotin Compounds,Tin Research Institute, Greenford, England (1958)

36. W. P. Neumann, H. Niermann, and R. Sommer, Ann. 659: 27 (1962)

37. H. Niermann, Dissertation, Giessen (1961) Germany

38. W. P. Neumann, N. Niermann, and B. Schneider, Angew. Chem. 75: 790 (1963)

39. N. A. Adrova, M. M. Koton, and V. A. Klages, Vysokomol. Soedineniya 3: 1041 (1961)

40. W. P. Neumann and R. Sommer, Angew. Chem. 75: 788 (1963)

41. M. C. Henry and J. G. Noltes, J. Am. Chem. Soc. 82: 561 (1960)

42. M. C. Henry and J. G. Noltes, ibid. 82: 558 (1960)

43. W. P. Neumann and R. Sommer, Angew. Chem. 76: 52 (1964)

44. W. J. Archibald, J. Phys. Chem. 51: 1204 (1947)

45. G. J. M. van der Kerk, J. G. Noltes, and J. G. A. Luijten, J. Appl. Chem. 7: 366(1957)

46. M. C. Henry and J. G. Noltes, J. Am. Chem. Soc. 82: 555 (1960)

47. R. Mathis-NoZl, M. Lesbre, and I. S. de Rooh, Compt. rend. 243: 251 (1956)

48. M. Lesbre and J. Satge, Compt. rend. 250: 2220 (1960)

49. J. R. Leebrick and H. E. Ramsden, J. Org. Chem. 23: 935 (1958)

50. H. Gilman, D. J. Peterson, and D. Wittenberg, Chemistry and Industry (1958) 1479

51. D. T. Mowry, M. Renoll, and W. F. Huber, J. Am. Chem. Soc. 68: 1105 (1946)

52. A. D. Petrov, E. A. Chernyshev, and N. G. Tolstikova, Doklady Akad. Nauk SSSR,118: 957 (1958)

53. W. V. Korshak, A. M. Polyakova, V. F. Mironov, and A. D. Petrov, Izvest. Akad.Nauk SSSR, Otdel. Khim. Nauk 1959: 178

54. A. M. Polyakova, A. A. Sakharova, E. A. Chernyshev, T. L. Krasnova, V. V. Korshak,and A. D. Petrov, Vysokomol. Soedineniya 5: 353 (1963)

55. A. M. Polyakova, V. V. Korshak, and E. S. Tambovtseva, Vysokomol. Soedineniya 3:662 (1961)

90

AFML-TR-65-192

REFERENCES (Continued)

56. G. Greber and G. Egle, Makromol, Chem. 64: 207 (1963) (see also references citedin Reference 22)

57. V. V. Korshak, A. M. Polyakova, and E. S. Tambovtseva, Vysokomol. Soedineniya 1:

1021 (1959) (see also references cited in Reference 22)

58. 'G. Bier, Angew. Chem. 73: 186 (1961)

59. Montecantini, Ger. 1,091,760; C.A. 55: 25371 (1961)

60. D. A. Kochkin and Yu. P. Novichenko, USSR 139,833; C.A. 56: 8 7 4 4g (1962)

61. D. A. Kochkin and Yu. P. Novichenko, USSR 139,834; C.A. 56: 7516h (1962)

62. V. Gutmann and A. Meller, Monatsh. Chem. 91: 519 (1960)

63. L. Spialter, D. C. Priest, and C. W. Harris, J. Am. Chem. Soc. 77: 6227 (1955)

64. H. A. Clark, A. F. Gordon, C. W. Young, and M. J. Hunter, J. Am. Chem. Soc. 73:3798 (1951)

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66. V. L. Hansley, Ind. Eng. Chem. 43: 1759 (1951)

67. H. GListen and L. Horner,gA__ew. Chem. 74: 586 (1962)

68. G. J. M. van der Kerk, H. G. J. Overmars, and G. M. van der Want, Rec.trav.chim.74: 1301 (1955)

69. G. J. M. van der Kerk and J. G. A. Luijten, J. Appl. Chem. 6: 93 (1956)

70. W. Peters, Ber. 38: 2567 (1905)

71. A. T. Dann and W. Davies, J. Chem. Soc. (1929) 1051

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73. A. Ya. Yakubovich, S. P. Makarov, V. A. Ginsburg, G. I. Gavrilov, and E. N. Merkulova,

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77. C. Tamborski, F. E. Ford, and E. J. Soloski, J. Org. Chem. 28: 181 (1963)

91

AFML-TR-65-192

REFERENCES (Continued)

78. H. Gilman and R. A. Tomasi, J. Org. Chem 27: 3647 (1962)

79. G. Wittig, E. Hahn, and W. Tochtermann, Ber. 95: 431 (1962)

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85. J. J. Miller, J. Org. Chem. 26: 3583 (1961)

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87. J. G. Noltes, M. C. Henry, and M. J. Janssen, Chemistry and Industry_ (1959) 298

92

UNCIASSIFIEDSecurity Classification

DOCUMENT CONTROL DATA - R&D(Security clasaification of title, body of abstract and indexing annotation must be entered when the overall report is classified)

1. ORIGINATING ACTIVITY (Corporate author) ]2a. REPORT SECURITY C LASSIFICATION

Institute for Organic Chemistry, T.N.O.j UnclassifiedUtrecht, The Netherlands 2b. GROUP

3. REPORT TITLE

THE SYNTHESIS OF GROUP IV OW3ANONETALLIC POLYMERS AND RELATED COMPW00DS

4. DESCRIPTIVE NOTES (Type of report and inclusive date@)

Summary Technical Report (March 1959 - February 1964)S. AUTHOR(S) (Last name, first name, Initial)

Leusink, A. J., Noltes, J. G., Budding, He A., and Van der Kerk, G. J. K.

6. REPORT DATE 74. TOTAL NO. OF PAGES 7b. NO. OF RXF"

December 1965 981 87an. CONTRACT OR GRANT NO. AF 61(052)-218 a,,. ORIGINATOR-$ REPORT NUMMER(S)

b. PROJECT NO. 7342

"Task No. 734203 9b R TRPORT NO(S) (Any other numbers .• otmay be esaieed

d. AFML-TR-65-1 92

10. AVA ILABILITY/LIMITATION NOTICES

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY

Nonmetallic Materials Division, Air ForceNkterials Laboratory, Research & TechnologyDiv., Air Force Systems Command, WPAFB, 0.

13. ABSTRACT

The synthesis and characterization have been described of linear polymershaving a carbon chain regularly interrupted by the Group IV elements silicon,germanium, tin or lead. Such polymers have been obtained by means of: (a) poly-addition reactions involving an organotin dihydride and either a dienic, a diynicor a monoynic compound; (b) Wurtz-type poly-condensations involving appropriatecombinations of p-chlorophenyl and chloro derivatives of. the Group IV elements.

The synthesis and polymerization of vinyl-type IVth group organometallicmonomers is dealt with briefly.

Furthermore, interesting IVth group metal-containing heterocycles havebeen prepared and also a few polymers, containing in addition to Group IV atomsother hetero-elements in their backbone.

All polymer-forming reactions have been studied by carrying out modelreactions on a low-molecular weight level.

DD JAN 1473 UNCLASSIFIEDSeurity Classificalton

UNCLASSIFIEDSecurity Classification

14 LINK A LINK 8 LINK CKEY WORDS ROLE WT ROLE WT ROLE WT

PolymersInorganic PolymersOrganometal lic CompoundsSilicon CompoundsTin CompoundsGermanium CompoundsLead Compounds

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UNCIASSIFIEDSecurity Classification