IR

O F

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

A R S E N I C

R . R . S h a g i d u l l i n , I . A . L a m a n o v a , L . A . P a v l o v a , a n d K . I . K u z ' m i n

UDC 543.422.4:547.1'119

To conf i rm the s t ruc tu re of the compounds (I)-(XXVI1) produced e a r l i e r [1], we studied their IR s p e c - t r a (Table 1). The valence v ibra t ion of the C--C bond of ( I - IV)is mani fes ted b y a weak band in the region of ~2025-2030 cm -1. This value is apprec iab ly lowered in compar i son with the f requencies for monosubst i tuted alkynes (vC-C 2100-2140 cm - i ) . And yet , it ag rees with the data of [2-4], where it is noted that the in t ro - duction of Si, Sn, and P into the c~-position to the acetylene group substant ia l ly lowers the f requency of the Vc=_ C vibra t ion. This is explained by the specif ic in teract ion of the 7r-electrons of the C------C bond with the d -o rb i t a l s of Si, Sn, and P; m o r e o v e r , it is a s sumed that the indicated in teract ion should dec rea se f r o m Si to Sn and Snto P[2], and, consequently, by analogy f r o m P to As as well . The appearance of Vc=_ C for o rg an s - a r sen ic compounds in a m o r e low-f requency region in compar i son with organophosphorus analogs [4, 5], is evidence of the p r e s ence not only of the indicated resonance interact ion, but also of an effect of the mass of the subst i tuent a tom for the C-----C bond.

In the region of the va lence v ibra t ions v C - C _ H in the spec t r a of compounds (1)-(IV), an a s y m m e t r i c a l band 3290-3300 cm -1 with a low-frequency shoulder 3280 cm -1, d i sappear ing in a solution of n-hexane, is obse rved . It was noted e a r l i e r [2, 6] that acetylene compounds a re capable of fo rming 7r-complexes, as well as hydrogen bonds. The acid p rope r t i e s of the - C - - C - H group depend on the f ract ional posi t ive charge of hydrogen. The p r r -dv effect will evidently inc rease it, p romot ing the fo rmat ion of H-bonds . In ag reemen t with a number of authors [2, 5], in this case we can a s s u m e the p r e sence of s e l f - a s soc ia t ion with the f o r m a - tion of complexes , for example , of the following type,

R~As--C~--~C--H t I i r

H--C~--C--AsR2

which a re the cause of the above-ment ioned spli t t ing of the band v=-c_ H for (I)-(IV).

In disubst i tuted a r sen ic ace ty lenes (VI)-(X), the v ibra t ion of the C--C bond is mani fes ted by a band of medium intensi ty ~2170 cm -i , which, jus t as for monosubst i tuted (1)-(V), is cons iderably lower than Z,C- C of disubst i tuted aceylenes (2260-2190 cm-1). A substant ia l dec rea se in the f requency and intensity of V c - C is a lso obse rved in (X), which has As a toms as both subst i tuents . The introduction of a hydroxyl group into d ia lky la rs inoace ty lene compounds (XIII)-(XIV) leads to a supp lementa ry shift of VC=_C in compar i son with (VI)-(IX) of ~30 cm -i , which is explained by the poss ib i l i ty of the fo rmat ion o f a h y d r o g e n b o n d . The inc rease in Vc___ C in the t rans i t ion f r o m secondary alcohols (XIII)-(XIV) to t e r t i a ry alcohols (XV)-(XVI) is mos t l ikely due to a change in the shape of the v ibra t ions of the C------C group, in accord with [2, 7].

The f requency of the valence v ibra t ions of the carbonyl group V c - O for (XVII)-(XXI) appears in a band at 1680 cm -i, which is cons iderably lower than the usual value for unconjugated aliphatic ketones (,.,1720 cm- i ) . The cause of this is apparent ly conjugation of the carbonyl group with the C--C bond [8]. This should also explain the dec r ea s e in V c - C for (XV1)-(XXI) by ~30 cm -I in compar i son with (VI)-(IX).

The carbonyl absorpt ion bands of e s t e r s of carboxyl ic acids l ie in the region of ~1735-1750 em -l . The shift of Vc= O in ethyl e s t e r s of d ia lkylars inylace ty lenic acids (XXV)-(XXVII) to 1710 cm -i is explained by an effect of conjugation of the carbonyl group with the C--=C bond and agrees with the l i t e ra tu re data for

A . E . A r b u z o v Institute of Organic and Phys ica l Chemis t ry , Academy of Sciences of the USSR. S . M . .... Kirov Kazan ' Chemicotechnological Inst i tute. T rans la t ed f r o m Izves t iya Akademii Nauk SSSR, Seriya Khimi- cheskaya, No. 8, pp. 1708-1710, August, 1972. Original a r t i c le submit ted F e b r u a r y 8, 1971.

1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher. A copy of this article is available from the publisher for $15.00.

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TAB LE 1

Number

I

II

III

IV V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII XIX XX XXI XXII XXIII XXIV XXV XXVI XXVII

Compound C~C

(CeHa)2AsC--=CH

(CaHT)~AsC=CH

(CsHn) 2AsC~CH

(C6H13hAsC~CH. (C3HT)zAsC=--CH T (C2H 5)~AsC--C--CsHll

I (C4Hg)2AsC--C--CHs-- N(C2Hs)~ (C4Hg)2AsC--C--C~Hn (C4Hg)2AsC--C--C4H9 I [(C6HI3)~AsC--]2 (C2Hs)sAsC--C--CH2-- N(C2H s)s ] (C3HT)2AsC--C--CH2-- N(C~ H~)~ (C~Hs)~AsC--C--CH(OH)--C~Hs (C~Hs)~AsC----C--CH(OH)--C~H~4 (C~Hs)~AsC--C--C(OH)(CHs)C~H ~ (C~Hs)~AsC------C--C(OH)(CHs)-- C~Hs-~ (CsH s)~AsC--=C--C(0)--CHs (C~H ~)~AsC------C--C(O)--C~H s (CsH~)~AsC------C--C(O)--CHa (CsH~)~AsC--C--C(O)--C~H~ (CaH~)~AsC--C--C(O)--CH ~ (C~H ~)~AsC=__C--C00H (C~H:):AsC--C--C00H (C~H~)~AsC__----C--COOH (C~H ~)~AsC~_C--COOC~H~ (C~H~)~AsC----__C--COOC~H~ (CaH~)~AsC____C--COOC~H a

~026 w

2024 w

~029 w

2026,w 2030.w 2170 s 2t57w 2t68s 2170m 1960v~ 2i50w 2t60w 2t35w 2135w 2t65w 2t65.w 2i38 S 2135s 2136vs 2135v~ 2t37v: 2t65s 2t65s 21655 i2t65s 12i65s 12165s

C~O

16[ Ovs 16~ 0 vs i6~ Ors i6~ Ors 16~ 0 vs t6 c, 5vs i6~ 0 vs 1610vs t7'. 0vs t7! 0vs i7'0vs

*vs) very ~rong; s) s~ong; m) medium; w) weak; vw)very weak.

~Inn-hexane.

,cm

---~CH OH

3280 3300s 3275 3290s 3282 33005 3280 3302s 3304s

3i00--3600 3100--3600 3200--3600 3200--3600

VC= O of the e s t e r group of a ce ty l ene compounds [9]. A c e r t a i n d e c r e a s e in the v i b r a t i o n f r equency VC= O of ~ 10 cm -1 in d i a l k y l a r s i n y l a c e t y l e n i c ac ids (XXII)-(XXIV) in c o m p a r i s o n with (XXV)-(XZXVII) should be exp la ined by a hyd rogen bond be tween the hydroxyl and the ca rbony l group, which p lays the ro l e of a p ro ton a c c e p t o r . The f r equency 2165 cm -1 in (XXI1)-(XXIV) and (XXV)-(XXVI1) c o r r e s p o n d s to the va l ence v i b r a - t ions of the C----C bond and is l owered in c o m p a r i s o n with the ana logous ace ty l en i c compounds , which i n - d ica tes the p o s s i b i l i t y of c o n s e r v a t i o n of an effect of con juga t ion of the ~r-e lect rons of the C--C bond with the d - o r b i t a l s of the a r s e n i c a tom.

The data of the IR s p e c t r a of ace ty l ene d e r i v a t i v e s of o r g a n o a r s e n i c compounds a g r e e with the l i t e r a - t u r e data [10].

EXPERIMENTAL METHOD

The s p e c t r a we re ob ta ined on a UR-10 s p e c t r o p h o t o m e t e r . The condi t ions were s e l e c t e d a c c o r d i n g to the i n s t r u c t i o n s for the i n s t r u m e n t , with s l i t p r o g r a m 4. The s u b s t a n c e s w e r e i n v e s t i g a t e d be tween KBr p la tes in the f o r m of a drop or s u s p e n s i o n in l iquid p e t r o l a t u m .

CONCLUSIONS

I. The El spectra of 26 acetylene derivatives of trivalent arsenic were studied.

2. The introduction of an arsenic atom in the a-position to the acetylene group substantially lowers the frequency of the vibration of the C--=C group, which may be due both to specific interaction of the ~r-elec- irons of the C=C bond with the d-orbitals of the arsenic atom and to the effect of the mass of the latter.

3. Monosubstituted dialkylethynylarsines are capable of self-association with the formation of com- plexes with a hydrogen bond.

LITERATURE CITED

i~ K.LKuz'min and L.A.Pavlova, Zh.Obshch.Khim., 36, 1478 (1966); 37, 1399 (1967); 39, 1068, 1797 (1969); 40, 1112 (1970).

2. E.A. Gastilovich, D. N. Shigorin, and N. V. Komarov, Optika i Spektroskopiya, 16, 46 (1964).

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3. M.F. Shostakovskii, N. I. Shergina, E. I. Brodskaya, O. G. Yarosh, and N. V. Komarov, Dokl. Akad. Nauk SSSR, 158, 1143 (1964).

4. V.V.Tarasov, Ya.S. Arbisman, Yu.A.Kondrat'ev, and C. Z.Ivin, Zh.Obshch.Khim., 38, 130 (1968). 5. F.A.Miller and D.H. Lemman, Spectrochim.Acta, 23A, 1199 (1967). 6. M.F.Shostakovskii, Yu. L.Frolov, O.A. Zasyad,ko, A.I.Borisova, and A.Kh.Filippova, Izv.Akad,

Nauk SSSR, Ser.Khim., 2229 (1968). 7. E.A.Gastilovich and D.N.Shigorin, Optika i Spektroskopiya, 23, 622 (1967). 8. M.F.Shostakovskii, N.I. Shergina, G.I. Kogan, and N. V. Koma~'~ov, Izv. Akad. Nauk SSSR, Ser.Khim.,

189 (1964). 9. L.Bellamy, Infrared Spectra of Complex Molecules [Russian translation], IL (1963), p.262.

i0. J.Benaim, Comp.Rend., 261, 1996 (1965).

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