Indian Journal of ChemistryVol, 17A, June 1979. PP. 580-582

Preparation & Characterization of Some New Organotin (IV) HalideComplexes of Ditertiary-, Tritertiary- & Diarsino-phosphines

A. WALIA, N. D. SADANANI. P. N. KAPOOR & R. N. KAPOOR*Department of Chemistry, University of Delhi, Delhi 110007

Received 2 December 1978

Ditertiary-, trttertiary- and diarstno-phosphine complexes of dior~anotin(IV) dihalideshaving the general formula R,SnCl,(Pf-Pf), R2SnCl, (Pf=Pf), R2SnC12 (Pf-Pf-Pf) and R.SnCI,(As-Pf-As) [where R = Me, Et, n-Bu; Pf-Pf = bis-l,2-(diphenylphosphino)ethane; Pf=Pf=bis-l,2- (diphenylphosphino )ethylene ; Pf -Pf- Pf= bis-(2- diphenylphosphinoethyl)phenylphosphineand As-Pf-As=bis-(2-diphenylarsinoethyl)phenylphosphine] have been synthesized. The com-plexes have been characterized on the basis of elemental analysis, IR and Mossbauer spectraldata, electrical conductance data and molecular weight determination.

A·LARGE number of adducts of diorganotin(IV)halides of nitrogen and oxygen containingmono and multident atc ligands are known"?".

A survey of literature reveals that some phosphorusdonar ligands have also been used for the synthesisof addition complexes of organo tin (IV) halides'<P.In this paper we report our results on the reactionsof Me2SnC~, Et2SnC12 and n-Bu2SnC12 with bis-l ,Z-(diphenylphosphino) ethane, bis-l,2-(diphenylphos-phino) ethylene, bis-(Z-diphenylphosphinoethyl)-phe-nylphosphine and bis-(Z-diphenylarsinoethyl) phenyl-phosphine in anhydrous benzene.

Materials and MethodsAnalytical grade reagents and solvents were used

and the reaction were carried out an under abso-lutely anhydrous condition. Ditertiary-, tritertiary-and diarrinophosphine s were prepared by knownmethodsI4-16.

The adducts were synthesised by mixing thediorganotin(IV) halides and ligand in benzene in1:1 stoichiometry and stirring it for about 40 hr.The complex was cryst allised from benzene/a-hexanemixture and dried in vacuo.

Attempts to prepare l:Z (R2SnCl2: phosphine)adducts failed, since 1:1 compounds were alwaysobtained irrespective of the molar ratio of thereagents used in the synthetic procedure.

Carbon and hydrogen were estimated microana-lytically, chlorine as silver chloride and phosphorusas phosphoammonium molybdate. The IR spectrawere recorded on Perkin' Elmer IR-621 in caesiumiodide in the range 4000-Z00 crrr '. Electrical con-ductance were carried out in acetone and nitro-benzene on the Beckman conductivity bridge modelRC-18A. The molecular weights of the complexeswere determined in benzene using an ebuliometer(W.G. Pye, Cambridge, England).

Mossbauer studies were carried out using1l9d Sn(BaSn03) source held at room temperature. Sampleof compounds were finely powdered and cooled atliquid nitrogen temperature in a cryostat placed

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in a container made of thcrmocole. Temperaturewas monitored bv using a thermocouple. Themossbauer absorption spectra were obtained intransmission geometry using a Mossbauer spectro-meter in MCS mode in conjunction with 512 mul-tichannel analyser [nuclear data]. The gamma rayswere detected by a Harshaw N aI integral detector.The velocity calibration was done using a typicalsix-finger Mossbauer spectrum using an enrichediron absorber (NEN). Stability of the circuitarywas properly checked from time to time. Sufficientcounts were stored in each channel and the datafrom multichannel analyser were reduced by meansof a least square fitting program on an IBM 360computer.

Results and DiscussionAll the 'complexes are white to yellow and are

soluble in benzene and acetone. Complexes havesharp melting points (Table 1). The complexesare non-electrolytes in acetone and nitrobenzene«1·0 em- mol! rnho-'}.

The IR spectra (\lmax in cm-I) of diorganotindichlorides are knownl7olS. Two bands corres-ponding to Vas (Sn-C) and 'Is (Sn-C) are observedin the region 500-600. The adducts of dialkyl-tin (IV) halides exhibit a strong band f"ooJ 515 whichmay be attributed to the overlapping of the tin-carbon assymmetrical stretching vibration withthe ligand vibrationI9•2o. No band is observedin the spectra of the adducts in the range 340-360,whereas two bands due to 'Is (Sn-Cl) and vas(Sn-Cl)have been located in dialkyltin (IV) dihalides, ThevSn-Cl band appearing in the region Z70-Z90is lowered by about 100 cm-l in the spectra of theadducts. This provides indication for the coor-dination. This change is due to change in coor-dination number--. Due to increase in coordina-tion number, an increase in electronic charge ofSn would' result in an increase in percent ioniccharacter of the tin-halogen bonds. These changesin the frequencies together with the number of bands

WALIA et al.: PREPARATION & CHARACTERIZATION OF ORGANOTIN HALIDE COMPLEXES1

TABLE 1 - PHYSICAL PROPERTIES AND ANALYTICAL DATA OF DIORGANOTIN(IV) HALIDES ADDUCTS OF DITERTIARY-. . TRITERTIARY- AND DIARSINO-PHOSPHINES '

Complex Colour m.p. Calc, (found) (%)°C

C II P CI

Me2SnC12·Pf-Pf White 118-20 54·35 4'85 10·02 11·46(54·02) (4'73) (10'01) (11'21)

Me2SnCI2.P£.= Pf Cream 120-21 54·54 4·56 10'02 11·50(54'24) (4'34) (9'94) (11'38)

Me2SnCI2·Pf-Pf-Pi Pink 141-43 57·28 5·17 4·10 9·37(57'10) (5'02) (4'02) (9,12)

Me2SnCI2·As-Pi-As Cream 137-38 51-30 4'63 3-63 8·40(51'26) (4'48) (3'51) (8'37)

Et2SnCI2·Pf-Pi do 74-76 55·00 5·19 9'46 10'S3(54'78) (5'15) (9'39) (10'81)

Et2SnCl~.Pf= Pf do 78-81 55·95 4·96 9·63 11;01(55'83) (4-88) (%0) (10'98) .

Et2SnCI2·Pf-Pf-Pi Yellow 145-47 58'34 5·50 11'88 9·00(58'30) (5'48) (11'S2) (S'84)

Et2SnCI2·As-Pi-As White 151-52 52·47 4·95 3·56 S'15(52-45) (4'72) (3-48) (8·08)

n-Bu2SnCI2·Pf-Pi Cream 142-44 58·11 5·88 8·82 . 10·19(58'00) (5'76) (8'74) (10'12)

n-Bu2SnCI2·Pf=Pf do 147-48 58'28 5·71 8'85 10·12(58'lS) (5,48) (8'62) (10'02)

n-Bu.SnCI a- pf-Pf-Pf YellOW 60·11 6·08 11·09 8'45

160-61(60'04) (5'94) (10.88) (8'28)

n-Bu.SnCI2·As-Pi-As .White 54·46 5;51 3·34 7·66(54'29) (5-40) (3'29) (7·57)

pi-Pi = bis-l,2-(diphenylphosphino)ethane .Pf=Pf = bis-l,2-(:liphenylphosphino)ethylenePf-Pf-Pf = bi~-(2-diphenylpho~phinoethyl)phenylphosphine.As-Pi-As = blS-(2-dlphenylarsmoethyl)phenylphosphine.

appearing in the spectra of the complexes have beenused to elucidate their structure.

In the spectra of the dialkyltin dichloride adducts,a strong new band appearing in the range 360-385may be tentatively assigned to P~Sn vibration-s.

Mossbauer spectra of few of the complexes havebeen measured in order to support the structureof the complexes. 119Sn Mossbauer isomer shift(3), quadrupole splitting (Ll) and line width (T) aregiven in Table 2.

The magnitude of the ratio of quadrupole splittingto the isomer shift was taken as a measure of coor-dination number. The value of the ratio as 1·8 orlower is indication of 4-coordination number. Butif the value is higher than 1·8, then the tin atomprobably has the coordination number five or six23,24.

In the complexes of dialkyltin dichloride withditertiaryphosphines, the ratio of the quadrupolesplitting to isomer shift is found to be greater than2·1. In the case of Me2SnC12·Ph2PCH2CH2PPh2it is found to be 2·6.

The value of isomer shift and quadrupole splittingin case of Me2SnC12.Ph2PCH2CH2PPh2 complexesare 1·381 mrnjsec and 3·921 mm/sec respectively ..These closely resemble those already reported forsix-coordinated compounds-". In the case of. l\~e2-SnC12• triphos, isomer shift and quadrupole splittingvalues are 1·102 mmjsec and 3·805 mmjsec respe~-t.ively. These values suggest that the complex IS

penta-coordinated with triphos behaving as mono-dentate ligand26• In triphos central phosphorusatom is acting as a donor atom as it is more basicthan the other two phosphorus atoms.

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TABLE 2 - MaSSB \UER SPECTRA OF DIORGANOTIN(IV)HALIDES COMPLEXES OF DITERTIARY-, TRITERTIARY AND

DIARSINO-PHOSPHINES

Complex Isomer Quadru- r1 r2shift pole (mm/ (mm/

(mm/scc) splitting see) see)(mm/scc)

Me2SnCIa- Pf- Pi 1·381 ±·02 3·921±·02 0·58 0·56Me2SnCI2Pf- Pf- Pf H02±'02 3·S0S±·02 0·48 0·49n-Bu2SnCI2As- Pf- 1-312±·02 3·752±·O2 0·52 0·53

As

PI-PI = bis-1,2-(diphenylphosphino)ethanePi-PI-Pi = bis-(2-diphenylphosphinoethyl)phenylphosphineAs-Pi-As = bis-(2-diphenylarsinoethyl)phenylphosphine

III

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INDIAN J. CREM., VOL. 17A, JUNE 1979

In the case of Bu2SnCl2.diarphos the isomer shiftand quadrupole splitting values are 1·312 mm/secand 3·752 mm/sec respectively, indicating that thecomplex is five-coordinatedw, and diarphos behavesas a monodentate ligand and phosphorus as a donoratom. Phosphorus atom in diarphos is more basicand thus acts as a donor atom. It is supportedby the IR spectrum also.

The molecular weight determinations of all thecomplexes show them to be monomeric.

Attempts to prepare 1:2 R2SnC12 adducts withPf-Pf, Pf=Pf, Pf-Pf-Pf and As-Pf-As failed, since1:1 complexes are always obtained irrespectiveof the ratio of the ligand used in the synthetic pro-cedure.

So on the basis of elemental analysis, IR spectra,Mossbauer spectra, electrical conductance and mole-cular weight data, structures (I-IV) are assigned tothe adducts. .

AcknowledgementTwo of the authors (A.W. and N.D.S.) thank the

UGC, New Delhi, for the award of junior researchfellowships.

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