U L T R A V I O L E T S P E C T R A O F S E L E N O P H O S P H O R Y L

C O M P O U N D S

R . R . S h a g i d u l l i n , A . V. C h e r n o v a , I . A. N u r e t d i n o v , G. M . D o r o s h k i n a , a n d E . V. B a y a n d i n a

UDC 543.422.6: 547.1' 118

Prev ious ly we had shown that absorpt ion bands a r e obse rved in the UV spec t r a of th io- and se leno- phosphoryl compounds that a r e caused by the e lec t ronic t rans i t ions in the P = S(Se) group [1,2]. The na ture of the t r ans i t ions for the thiophosphoryl compounds was d i scussed in [2]. The UV s p e c t r a of a number of sa tu ra ted se lenophosphoryl compounds a re d i scussed in the p resen t communica t ion (Table 1). The l i t e r - a ture data on this c l a s s of e lec t ronic spec t r a a re l imi ted to a d i scuss ion of compounds of type

) P - ( S e ) ~ - P ( [3]. On the bas i s of the s impl i f ied d i ag ram of the m o l e c u l a r o rb i ta l s (MO), proposed fo r I1 II --

So Se dise lenides [4] and the complexes of diethyl selenophosphonate with me t a l s (Cr, Ro, and Ir) [5], the authors of [3] l ink the absorpt ion bands obse rved in the s p e c t r a of these compounds main ly to the MO that co r r e spond to the Se--Se bonds. The authors of [3] do not cons ider the poss ib i l i ty of the selenophosphoryl group exhibiting absorpt ion, although the re a re indications that another band, bes ides the one in t e rp re t ed by them, is p resen t in the s p e c t r a of some of the compounds given in t he i r paper .

F r o m Table 1 it can be seen that e i ther two or th ree bands a re obse rved in the spec t r a of the studied compounds (I)-(XXI). A dist inct in te r re la t ionsh ip between the posit ion of the long-wave absorpt ion m a x i - m u m and the na ture of the subst i tuents , a t tached to the phosphorus atom, can be t r a c e d in a number of the compounds (I)-(III), and the acid chlor ides (IV)-(XI), monoamides (VIII), (XIX), and (XX), and d lamides (VII), (XV), (XVI), and (XXI) of the se lenophosphoric acids . The same as in the case of thiophosphorus compounds [2], the d i scussed band exhibits hypsochromic shift as the donor p r o p e r t i e s of the va r i ed sub-

sti tuent a re enhanced: kRO < kNR 2 < k R < kC1.

In a numb er of c a se s an inc rease in the po la r i ty of the solvent i s accompanied by a hypsochromic shift of the long-wave band (see Table 1). Fo r solutions of diethyl chloroselenophosphinate in aprot ic so l - vents , capable of fo rming a hydrogen bond, the highest value of Ak i s obse rved when t r i f luoroace t ic acid i s used as the solvent (Table 2).

As a resu l t , the long-wave band, judging by the c h a r a c t e r of how it i s affected by the na ture of the subst i tuents on the phosphorus a tom and the po la r i ty of the solvent, co r r e sponds , the s ame as in the s p e c t r a of thiophosphoryl compounds [2], to n ~ v*- t rans i t ion . The high intensi ty of the band is appa- ren t ly assoc ia ted with the fact that the d i scussed t rans i t ion a lso includes in t r amolecu la r charge t r a n s f e r f r o m the se lenium a tom to the vacant phosphorus o rb i ta l s .

An ana lys i s of two other bands, which, by analogy with thiophosphoryl compounds [2], should be ass igned to the v -~ v* and n -~ o'* t r ans i t ions , i s difficult. In the s p e c t r a of mos t of the d i scussed c o m - pounds the v ~ v* band does not fall in the opera t ing range of the spec t ropho tomete r (compounds (II), (III), (VIII), (XII)-(XXI), while the second m a x i m u m e i ther l i e s at the lower l imi t of this r ange [compounds (i_I), (HI), (VIII), (XII)-(XXI)], o r e l se it is supe r imposed on the f i r s t band [compounds (IV)-(VII)] (see Table 1). Only in the spec t r a of the alkyl d ichloroselenophosphonates [compounds (IX)-(XI)] do all th ree bands ap- pea r separa te ly . However , only the length of the alkyl rad ica l i s va r i ed in this s e r i e s of compounds, which, as can be seen f r o m Table 1, has l i t t le effect on k m a x.

A. E . Arbuzov Insti tute of Organic and Physica l C h e m i s t r y , Kazan Branch of the Academy of Sci- ences of the USSR. T rans l a t ed f r o m Izves t iya Akademii Nauk SSSR, Ser iya Khimicheskaya, No . l , pp.184- 187, January , 1976. Original a r t ic le submit ted June 3, 1975.

�9 76 Plenum Publishing Corporation, 22 7 West 17th Street, New York, N. Y. 1.0011. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher for $15.00.

174

TA

BL

E 1

. U

ltra

vio

let

Sp

ectr

a of

Sel

enop

hosp

hory

l C

ompo

unds

Com

poun

d (i)

(lI)

(lid

(i

v)

(v)

(vI)

(vii

) (V

III)

(i

x)

(x)

(xi)

(X

lI)

(XH

I)

(xlv

)

(xv)

(x

vi)

(xvi

i)

(XV

III)

(X

lX)

(xx)

(x

xi)

Form

ula

(CaH

g)aP

(So)

[ (

CH

a)2N

bP(S

e)

(C2H

aO)a

P(S

e)

(C~H

a)2P

(Se)

CI

(C4H

g)~P

(Se)

Ci *

(t-

CaH

oO)u

P(Se

)C1

[ (C

2Ha)

2N ]e

P(Se

)CI

(CeH

BO

) [(C

eHs)

~N 1

P(Se

)CI

CH

aP (S

e) C

l~

C2H

~P(S

e)C

I~

CdI

gP(S

e)C

lu *

(C

HaO

) (O

.,tta

).oP(

Se)

(C~H

aO) (

C2I

ta)2

P(Se

)

(C~l

cIaS

) (C

~Ha)

uP(S

e)

(C2H

~O) [

(C~H

s)~N

]~P(

So)

(CH

e=C

HC

HeO

) [ (

CH

shN

]2P(

Se)

(CH30)2(CHa)P(Se)

(C2H

50) ~

(C2H

a) P

(So)

(C

2HaO

)~[ (C

~Ha)

2N ] e

(se)

I (

CH

3)2N

] (C

2Ha)

~P (S

e)

[ (CH

a)~N

]~(C2Ha)P(Se)

195(

4,i8

)

t95(

4,03

) i9

2 (4

,04)

i9

2(3,

92)

~20

i (3,

90)

* T

he s

pect

rum

was

tak

en o

n an

SF-

8 sp

ectr

opho

tom

eter

.

197,

,t

2)

t94

,22)

20i (

3,43

) i9

o(4,

o8)

t94(

3,91

) t 9

8 (4,

20)

~i9

8(4,

i2)

~t97

(3,8

7) X

max

, nm

(lo

g e)

sh.

208(

4,06

) 19

4(4,

t4)

200(

4,(~

3)

t90(

3,92

)

194(

4,20

) 23

4(3,

77)

231 (

3,75

) 23

4 (3,

71)

232(

3,71

) 22

7 (4,

08)

239(

3,7t

) t9

t(4,

09)

~t94

(4,0

3)

t92(

4,05

) ~

i94(

4,tl

)

~t92

(4,3

5)

~192

(4,

t3)

t 96 (

3,96

) --

t96(

4,06

) ~t

92(4

,03)

~t

95(4

,19)

~

i94(

4, O

9)

--t9

4(4,

tt)

n~

*t*

238(

3,53

) 22

9(3,

76)

sh.

225(

3,76

) 21

3(3,

55)

260(

3, 6

0)

258(

3,59

) 25

5 (3,

55)

265(

3,89

) 24

4{3,

26)

242 (

3,26

) 25

2(3,

38)

247 (

3,24

) 28

0(3,

19)

273(

3,12

) 27

6 (3,

i6)

270(

3, t0

) 27

0(3,

48)

280(

3,t7

) sh

. 2i

7(3,

84)

sh. 2

13(3

,90)

sh

. 217

(3,8

0)

sh. 2

11(3

,90)

26

5(3,

60)

262(

3,30

) 26

2(3,

52)

227(

3,91

) sh

. 22

5(3,

80)

sh.

217(

3,77

) sh

. 2t7

(3,7

2)

sh. 2

17(3

,69)

sh

. 23

3(3,

73)

sh.

232(

3,70

) sh

. 23

0(3,

64)

So lv

ent

Eth

ane,

et

hano

l H

exan

e E

than

ol

Hex

ane,

eth

anol

H

exan

e E

than

ol

Ace

toni

tril

e C

yc lo

he xa

ne

ttex

ane

Eth

anol

H

exan

e

))

teha

no 1

x an

e

For

mic

aci

d T

rifl

uoro

acet

ic a

cid

Cyc

lohe

xane

H

exan

e E

than

ol

Hex

ane

Eth

anol

H

exan

e E

than

ol

Ace

toni

tril

e H

exan

e, e

than

ol

The

sam

e

Hex

ane

Eth

anol

r

log e

f 200 250 30g

,t, n m

Fig.l

log q~o

3~0

Z~O \

200 25g 300 ,t~ nm

Fig.2 Fig.1. Ul t ravio le t spec t r a of solutions of (C2H~)z(C2HsO)P(Se) (1) and (CzHs)2(C4HsSe)P(O) (2) in n -hexane .

Fig.2. Ul t ravio le t spec t r a of solutions of (C2H50)2(C2H~)P(Se) (1) and (C2H50)(C2HsSe)(C2Hs)P(O) (2) in n -hexane .

TABLF~ 2. Posi t ion of Maximum of Long- Wave Band in Spect rum of Diethyl Chloro- selenophosphinate as a Function of the Solvent

Solvent

n-ttexane Ethano 1 Acetonitrile u.tN HC104 inCI-hCN Formic acid Acetic acid Trifluoroacetic acid

Xmax.nm (log ~)

26o(3,6o) 258 (3,56) 255(8,55) 254 (3,58) 25i(3,40) 256 (3,59) 240(3,55)

Ax *, nm

0 2 5 6 9 4

20

* AX = kMa x :in hexane - kma x in a protic solvent.

Despi te the shown in te r re la t ionsh ip between the posit ion of the long-wave m a x i m u m in the spec t r a of the th io- and selenophosphoryl compounds and the na ture of the subst i tuents on the phosphorus a tom, Urea x fa i ls to c o r r e l a t e with e i the r the ~ p constants of these subst i tu- ents o f with such c h a r a c t e r i s t i c s of the compounds as the ene rgy of the H bond, the f requency of the v p =S(Se) s t re tching v ibra t ions in the IR spec t r a , the dipole m o - men t s , the spin -- spin coupling constants , and the ch emi - cal shif ts in the Sip NMR spec t ra . The absence of a s i m - ple co r re l a t ion between the indicated p a r a m e t e r s is ev i - dently not accidental and is a s soc ia ted with the fact that the energy of the d i scussed t rans i t ion is de te rmined both by the p r o p e r t i e s of the nonbonding a tomic orbi ta l of the

he t e roa tom (sulfur o r selenium) and by the p r o p e r t i e s of the vacant M e , the c h a r a c t e r i s t i c s of which a re not avai lable to us at the p resen t t ime . It should be ment ioned that even fo r such a widely studied c l a s s of compounds as the sa tu ra ted earbonyl compounds only one co r re la t ion equation, which r e l a t e s the Av of the n -~ ~* t rans i t ion to the ~* constants of the subst i tuents , is known [6, 7]. But only the additive c h a r a c t e r of the substitution effect is a lso indicated in this equation, since only the n u m b e r of alkyl o r ha lo- alkyl groupings was var ied in the studied compounds.

The i somer i za t ion of the selenophosphoryl compounds to the selenol e s t e r s of phosphorus acids is accompanied by substant ial changes in the spec t ra l p ic ture . These changes consis t in a ba thochromic shift of the long-wave band and a sha rp dec rea se in i ts intensi ty for the selenol e s t e r (Figs.1 and 2). The compounds shown in Fig.1 can be r ega rded as being i s o m e r s , s ince, as was shown above, replacing the ethyl rad ica l by butyl does not cause substantial changes in k m a x. The absorpt ion obse rved in the spec t r a (C2Hs)2(C4HgSe)P(O) and (C2Hs)(C2H50)(C2HsSe)P(O) in the 250-270 r tmreg iou should be re la ted , the s ame as in the case of the thiol e s t e r s of phosphorus acids [2], to the e lec t ron t rans i t ion in the P--Se bond. The nature of this t rans i t ion can apparent ly be made specif ic via additional s tudies .

As a resu l t , the selenophosphoryl group, l ike the thiophosphoryl group, has ch romophore p rope r t i e s . The quite l a rge d i f fe rences in the posit ion and intensi ty of the bands of the se lene- and selenol i s o m e r s mmke i t poss ib le to use the UV spec t roscopy method fo r t he i r identification.

E X P E R I M E N T A L M E T H O D

The studied compounds were synthesized as desc r ibed in [8]. The UV spec t r a were obtained on a Specord UV-Vis automat ic record ing spee t ropho tomete r . The solvents were pur i f ied and made absolute in advance. The concentrat ion of the studied solutions was (3-5).10 -2 m o l e / l i t e r , and the cell th ickness was se lec ted so that the optical densi ty of the solutions was found in the range 0.2-0.8.

176

CONCLUSIONS

I. Absorption bands were observed in the UV spectra of saturated selenophosphory[ compounds that were attributed to the ~-~ ~*, n _~i ~., and n -* 0* transitions in the selenophosphoryl group.

2. l~t was proposed to use the UV spectroscopy method to study the selene--selene| isomerism in organophosphorus compounds.

i.

2.

3,

4. 5. 6. 7. 8.

LITERATURE CITED

R. 1~. Shagidullin, A. V. Chernova, I. A. Nuretdinov, G. M. Doroshkina, and E. V. Bayandina, Izv. Aksd. Nauk SSSR, Ser. Khirn., 197 (1975). R. R. Shagidullin, A. V. Chernova, I. A. Nuretdinov, G. M. Doroshkina, and E. V. Bayandina, Dold. A_kad. Nauk SSSR, 222, 897 (1975). IV[. V. Kudchadker, R. A. Zingaro, and K. g. Irgo[ic, Can. J. Chem., 46, 1415 (1968). G. ]3ergson, G. Claeson, and L. Schotte, Acta Chem. Soand., i__66, 1159 (1962). C. K. Jorgensen, Mol. Phys., 5, 485 (1962). R. 5~. C. Brownlee and R. D. Topsom, Spectrochim. Acta, 29A, 385 (1973). J. F,. Dubois and A. Bienvenue, Compt. Rend., 256, 5351 (1963). N. :?. Grechkin, I. A. Nuretdinov, N. A. Buina, and L. K. Nikonorova, Chemistry and Application of Or~;anophosphorus Compounds, Transactions of Fourth Conference [in Russian], Nau_ka (1972), p.350.

177