A B I L I T Y OF A s = S G R O U P TO F O R M T H E

H Y D R O G E N B O N D

R. R . S h a g i d u l l i n , S. V. I z o s i m o v a , a n d I . A . L a m a n o v a

UDC 543.422.4:541.571.9:547.558.2

It is known [1 ] that the P = S group is capable of forming the hydrogen bond by functioning as the p r o - ton accepter . Information on the involvement of the As = S group in the hydrogen bond is p rac t ica l ly ab- sent [2]. A s tudy of this problem is of undoubted interest , both f rom the standpoint of expanding the r e - s ea r ch on H bonds and in o rder to a sce r t a in the nature of the As = S group.

We s~udied the IR spec t ra in the region of the s t re tching vibrat ions of the OH group of the t e r n a r y mix tures : a r sen ic sulfides + phenol + CC14. The assoc ia tes of the a rsenic sulfides and phenol are mainly formed in these mix tures in a 1 : 1 rat io, which was established by measur ing the peak intensity Imax of

bound with change in the relat ive amount of the components, under the hydroxyl band of the bound phenol, v OH '

the condition of maintaining their total concentrat ion constant.

The enthalpy of format ion of the hydrogen bonds, - A t I , was calculated by three methods: by mea- suring the associa t ion constant Kasso c at var ious t empera tu res by the change in Imax of the v OH band of the f ree pl~enol, p rev ious ly cal ibrated with r e spec t to t empera tu re [3], by the shift AvOH of the hydroxyl band of phenol in the format ion of the H bond [4], and by the "intensi ty rule" [5].

The resul t s a re given in Table 1. As a rule, the - A H values obtained by the different methods coin- cide withir the l imits of experimental e r r o r .

When compar ing the shifts Av and the - A H energy values for the organoarsenic complexes and the analogous ~rganophosphorus compounds with phenol it should be mentioned that the enthalpy of format ion of the hydIogen bond involving the As = S group i s only sl ightly g rea te r than the - A H for the P = S group (see Table 1, compounds 1, 6, 7, and 8), and is considerably smal le r than for the As = O group in the analogous substitution, i.e., the As = S grouping fo rms more stable hydrogen bonds with phenol than does the P = S ~ o u p , but less stable bonds than does the As = O group.

TABLE 1

No. Compound

(C6H*)3As=S (p-CH3C~H4)3As~$ (C6H6)~C~HsAs=S p-BrC6H4(C~Hs)~As=S C6Hs(CeHs)2As=S (C2H~)3As=S

(C2Hs)~P~S Cdtffe.zHs)~As= 0 [9]

y, /ky, ] cm -I cm -1. from [4]

33i5 296 5,5 3300 31i 5,6 3290 32t 5,7 3277 334 5,9 3268 343 5,9 3242 369 6,2

- - 24i 4 ,9 321 5 7 7ii 8:6*

-AH, kcal/M

from [3] from [5]

- - 4,8 5,3 5,0 5~ 4,8 5,0 4,8 5,2 6,4 6,0

22 ~ Kassoc

i5,1

2~.5 27,0

* The band of the unassociated phenol is found at 3611 cm "1. Made more accurate on the basis of the "center of gravity" of the band [4].

A. E. Arbuzov Institute of Organic and Phys ica l Chemis t ry , Kazan :Branch of the Academy of Sci- ences of the USSR, and the V. I. Ul 'yanov-Lenin Kazan State Universi ty. Translated f rom Izves t iya Akad- emii Nauk SSSR, Ser iya Khimicheskaya, No, 12, pp. 2778-2779, December , 1973. Original ar t ic le sub- mitred May 8, 1973.

�9 1974 %nsultants Bureau, a division of Plenum Publishing Corporation, 227 ~/est 17th Street, New York, N. Y. 1001i. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording Qr otherwise, without written permission of the publisher. A copy of zhis article is available from the publisher for $15.00.

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Abound 1 VOH , cm-

360 6 5 300 4' 3

320

.,390 2 o / I

-2,8 -2,z/ -2,0 % 6 % 2 0 p

Fig. i. Shift in frequency &, bound of phenol as a func- v OH tion of the Kabachnik ~p con- stant. The numbers c o r r e - spond to those given in Table 1.

For the As = S group, the same as for the P = O and P = S groups ]1], a change in the stabil i ty of the hydrogen bond with phenol is observed as a function of the environment of the arsenic atom. In par t icu lar , within the l imits of the studied ser ies of compounds a good corre la t ion is obtained between Av and the Kaba- chnik constants (Fig. 1) [6].

CONCLUSIONS

The As = S group is capable of forming a hydrogen bond with phenol by functioning as the proton ac- ceptor, in which connection the p ro ton-accep tor capaci ty depends on the environment of the a rsenic atom. The stabil i ty of the formed hydrogen bonds is somewhat higher than for the P = S group, but it is cons ider- ably lower than for the As = O group.

i.

2.

3.

4. 5. 6. 7.

8.

9.

LITERATURE CITED

R. R. Shagidullin, I. P. Lipatova, L. I. Vachugova, and S. A. Samartseva, Dokl. Akad. Nauk SSSR, 202, 617 (1972). I%. R. Shagidullin, S. V. Izosimova, I. A. Lamanova, and Yu. G. Galyametdinov, Data of Scientific Conference, Institute of Organic and Physical Chemistry [in Russian], Kazan (1972), p. 211. G. C. Pimental and A. L. McClellan, The Hydrogen Bond [Russian translation], Mir (1964), p. 180. A. V. Iogansen and B. V. Rassadin, Zh. Prikl. Speklroskopii, Ii, 828 (1969). A. V. Iogansen, Teor. i Eksperim. Khim., 7, 302 (1971). T. A. Mastryukova and M. I. Kabachnik, Usp. Khim., 3_~8, 1751 (1969). R. R. Shagidullin, I. P. Lip~:tova, I. A. Nuretdinov, and S. P. Samartseva, Dokl. Akad. Nauk SSSR, 211, 1363 (1973). L. L Vachugova, I. P. Lipatova, S. A. Samartseva, and R. R. Shagidullin, Data of Scientific Con- ference, Institute of Organic and Physical Chemistry [in Russia~], Kazan (1971), p. 51. R. R. Shagidullin, I. A. Lamanova, L. V. Awakumova, and B. D. Chernokal'skii, Abstracts of Papers Delivered at Fifth All-Union Conference on the Chemistry of Organophosphorus Compounds [in Russian], Moscow (1972), p. 230.

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