VIBRATIONAL SPECTRA OF O R G A N O A R S E N I C COMPOUNDS

COMMUNICATION 6. IR SPECTRA OF ESTERS OF ARSINIC ACIDS *

R. R. Shagidullin and I. A. Lamanova UDC 5 4 3 . 4 2 2 . 4 + 5 4 7 . 2 6 ' 119

W e h a d e a r l i e r p u b l i s h e d d a t a o n V A s = 0 i n t h e IR s p e c t r a of a n u m b e r of e s t e r s of a r s i n i c a c i d s [2].

T h i s c o m m u n i c a t i o n p r e s e n t s a m o r e d e t a i l e d d i s c u s s i o n of t h e m a n d i n d i c a t e s t h e c h a r a c t e r i s t i c f e a t u r e s

o f o t h e r g r o u p s . We h a v e f o u n d no a n a l o g o u s d a t a in t h e l i t e r a t u r e .

W e o b t a i n t h e IR s p e c t r a of t h e f o l l o w i n g f o u r c o m p l e t e a n d 11 i n c o m p l e t e e s t e r s (F ig . 1 p r e s e n t s

s a m p l e s p e c t r o g r a m s ) :

(RO) aA s == O, 1 / = CII3, t C 2 H 5 , n-C3I[7, n-C~II~ ( R O ) z l V A s = O , R ' = CHs, C2H5 , n-C4H~, i-Cdt; ,

CH2 =: CIICH2, C6ItsCII2, t{ ,~ C2I{5, i-C3H7, n-C4Hg, n -CsIh i .

T h e f r a g m e n t f o r w h i c h we s h o u l d e x p e c t t h e p r e s e n c e of c h a r a c t e r i s t i c b a n d s i n t h e s e m o l e c u l e s a r e t he

f o l l o w i n g g r o u p s : 0 0

/ / (As)--O~C. As--O, As- -0, As=:0,

\ \ 0 C

a s w e l l a s t h e h y d r o c a r b o n r a d i c a l s R .

(As) - O - C . F i r s t of a l l , t h i s g r o u p i s m a n i f e s t e d , j u s t a s a m o n g t r i v a l e n t e s t e r s [3], b y a n i n t e n s e

b a n d a r o u n d 1000 c m - l . T h e m a x i m u m of t h i s b a n d i s s h i f t e d t o w a r d l o n g w a v e s a s t h e l e n g t h o f t h e r a d i c a l

* F o r t h e p r e c e d i n g c o m m u n i c a t i o n s e e [1]. T h e s p e c t r o g r a m of (CH30)3As = O is n o t c i t e d in F i g . 1. A s e p a r a t e a r t i c l e w i l l b e d e v o t e d to a d e t a i l e d

a n a l y s i s o f t h i s c o m p o u n d .

T A B L E I *

(CH~O)3As=0 (C2I{~O) sash0 Interpretation~ V, cm -I y, cm -I

2994 w 2985 s v=~CH3 2935 rn 'Va ~C~H2

2949 m 2900 rn %CH3 rl CII~ 2906 w 26 2845 rn 28

1485 w 6CH2 1462 m 1450 w 6~CH3

1395 m .~-CIIz 1450 m. (sh) 1370 w fi~CIIa

1310 w vCth 1176 w 1163 w - m J~ Out-of-planeplanar ]

1098 m fp-CII~ 1018 v. s (sh) ~ 1020 v. s 'V(As)--O--C J

998 v.s J 976 v. s (sh) 978 s Vhs=O

908 s-v. s ~ (o) -c -c 761 rn ?

710 m p~Ctlz 675 v. s 670 m. III v=,AsO3 650 m-s v~As03 560w ?

450 m-w ~ 6As--(ORh 490 m-s 400 m . J

~'Abbreviations:sh _ shoulder; v.s. - very strong; s - strong; m - medium; w - weak; b r - broad; ~r - fan; p _ pendulum; ~" - torsional vibrations. tThe interpretation was performed by analogy with [4,5].

A . E . A r b u z o v I n s t i t u t e of O r g a n i c a n d P h y s i c a l C h e m i s t r y , A c a d e m y of S c i e n c e s of t h e USSR.

T r a n s l a t e d f r o m I z v e s t i y a A k a d e m i i N a u k SSSR, S e r i y a K h i m i e h e s k a y a , No. 6, pp . 1 2 3 8 - 1 2 4 2 , J u n e , 1969 .

O r i g i n a l a r t i c l e s u b m i t t e d M a y 20, 1968 .

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TABLE 2

Groups V, c m - I

As-O AsO - - C

A s ' " OC

(O) As.-- OC

A s - - C a l

As - - Ph

As - - CI As - - II

~0) AsO -- t t A s = S O--CH2

x< I O--CH2

A s - - O - A s

As- -C=C--

I~aAs~- -NS 0 2 - -

880--980 1030 650 680 550

550--570 1590 1440 1080 1030 I000 5OO 390

2100 1600--2800 460--490

900 670 740

1620 1(!20 1100 1250

Intensity ill spectrum

IR Raman

V.S r'fl

S - V . S m - w

V,S ITI V.S W

S mS s m-w ' m

m w m w w w w m v.8 i n

Th V.S

S

S

V,S In V,S

V,S V,S

Literature !reference

2, 7, 8 3 3

i I

3,9 s I W A s 10 w I 11

re broad bands s 12

m 3 s 3

13

14

80

40

gO

!

I I I I ~ I ! I f r I ; I q i l ! ~ i I

i I i I I I l~f ~ I i t , tl , , ,

r I t ~ I I t ~I I r I i 1 , , , ....

go

4~0

3~00 dO00 2600 /gO0 f400 f000 800 700 600 YO0 7J, CTTI " [

Fig. i. IR spectra of esters: i) (C2IlsO)3As = O; 2) (C3H70)3As = O; 3) (C4H90)3As = O; 4) CHa(OC2Hs)2As = O; 5) C2Ha(OC2Hs)2As = Oo

i n c r e a s e s and for b r a n c h e d R. in m o s t c a s e s the band has a complex s t r u c t u r e , on account of the p r e s e n c e of

s e v e r a l ro t a t i ona l i s o m e r s .

Strong absorption bands in the region of 600-700 o o

/ em-lbelongto As--O and As/-O [3]. These bands

\ \ o c

as a rule, are complex, which is apparently due to the presence of various vibrations of the skeletons

(Vas and Vs), as well as of rotational isomers. The f r e q u e n c i e s with a m a x i m u m V A s - O in th is case a r e e l eva ted by 20-30 cm -1 in c o m p a r i s o n with VAs_ O of compounds of t r i v a l e n t a r s e n i c [3]. In t u r n , the h igher f r e que nc y and m o r e i n t e nse bands , which should be

o

a s s i g n e d to Vas As - O for the ske l e ton of As/--o, l ie \

o

above the c o r r e s p o n d i n g f r e q u e n c i e s of the v i b r a t i o n s o

of As--/o (700 and 690 cm -1, r e s p e c t i v e l y ) . The ethoxy \

c

group has a p ronounced double t VAs _ O" Compounds with b r a n c h e d r a d i c a l s have s i m p l e r bands , which is due to the s m a l l e r p o s s i b i l i t y of the f o r m a t i o n of v a r i - ous i s o m e r s in view of the vo luminous c h a r a c t e r of the s u b s t i t u e n t s .

The hydrocarbon radicals R in the investigated compounds are connected directly to the As atom or are contained in alkoxy groups. In the first case, the most characteristic bands are: for CH3:2980 s, 2930 m, 1410 m, 1280w, 880 s; C2Hs:1460 m, 1415 w, 1235 w, 742 m; C3H5:1420 w, 990 m (sh), 820 m n-C4Hg: 1420 w, 780 w, 760 w - m , 720 m; i-C4Hg: 1420 w (sh), 790 m, 493 w; C~IIsCII2:3070 w, 3040 w, 1610 w, 1504 m - w , 817/807 m - w , 760 m - s , 700 s, 465 m.

It should also be mentioned that the indicated characteristics are similar to those ofarsine oxides [1].

II/13

The c h a r a c t e r i s t i c bands of the alkoxy groups at As for the compounds unde r c o n s i d e r a t i o n l inc lud- ing the ( A s ) - O - C band] a r e the following*: CH30 :2994 w, 2949 m, 2906 w, 2845 m, 1460 m - w , 1180 w, 1010 v . s . , 760 m - w ; C2II50:2980 v . s . - s , 2930 s - m , 2900 m - s , 1485 w, 1450 w - m , 1390 m, 1370 w. sh, 1162 w, 1110 m, 1030 v .s , 910 v.s; C~HyO: 2970 s, 2945 s - m, 2890 m, 1480 m, 1400 m, 1290 w, 1260 w, 1155 w, 1060 s - m, 1040 s - m (sh), 960~" v.s; i-C3HTO: 2980 v . s , 2930 m - s, 2880 m, 1470 m, 1385 m - s, 1370 m - s , 1350 m - w ( s h ) , 1174 m - w , 1140 m, 1110 v . s - s , 1045w, 960 v.s~', 850 s, 435 m; CtHgO: 2960 v .s , 2940 s - v .s , 2880 s, 1465 m, 1435 w (sh), 1380 m, 1300 w, 1260 v.w, 1230 v.w, 1145 w, 1120 w,

1060 s, 1 0 2 0 s , 1005 s, 970v.s '~;CsH110; 2 9 6 0 v . s , 2 9 4 0 v . s , 2 8 8 0 s , 2 8 6 5 s (sh), 1470 w ,1410 w, 1380m, 1280 m, 1210 w, 1120 w, 1080 m, 1050 s, 980 v .s , 880 (900) s , 800 m.

Tab l e 1 p r e s e n t s as an example the i n t e r p r e t a t i o n of the IR s p e c t r a of the s i m p l e s t m e m b e r s of the s e r i e s that we inves t iga ted in t e r m s of the v a l e n c e - f o r c e app rox ima t ion .

As =O. We ident i f ied a ve ry i n t ense a b s o r p t i o n band at ~980 c m -1 for the comple t e e s t e r s and ~950 c m -~ for the i ncomple t e e s t e r s inves t iga ted with the va lence v i b r a t i o n s of this bond [2]. Somewhat l a t e r an ana logous a s s i g n m e n t for c e r t a i n comple t e e s t e r s was made in [6]. In the R a m a n s p e c t r a , which we ob ta ined for some of the compounds c i ted , VAs = O appea r s as a s h a r p l y po l a r i z e d l ine of r e l a t i v e l y m e d i u m in tens i ty .

T a b l e 2 p r e s e n t s a s u m m a r y of the c h a r a c t e r i s t i c f ea tu r e s of the v i b r a t i ona l s p e c t r a of o r g a n o a r s e n i c compounds {approximate va lues of the f r e q u e n c i e s a r e indica ted) , which we found and the l i t e r a t u r e va lues .

EXPERIMENTAL METHOD

The spectrograms were obtained on a UR-10 spectrophotometer (slit program 4, rate of scanning 50, time of movement of pen 32, width of amplifier band 2). The substances were transparent, colorless, ex- tremely hygroscopic liquids. All operations on preparation of the samples and recording were performed in a special chamber, to prevent contact with atmospheric moisture.

The authors would like to express their sincere gratitude to B. D. Chernokal'skii and K. I. Kuz'min for providing the compounds for the investigation.

C O N C L U S I O N S

1. The IR s p e c t r a of 15 e s t e r s of a r s i n i c ac ids w e r e ob ta ined and d i s c u s s e d .

2. The c h a r a c t e r i s t i c f e a t u r e s in the v i b r a t i o n a l s p e c t r a of o r g a n o a r s e n i c compounds a r e c i ted.

LITERATURE CITED

i. R.R. Shagidullin and I. A. Lamanova, Izv. Akad. Nauk SSSR, Ser. Khim., No. 5 (1969). 2. R.R. Shagidullin, I. A. Lamanova, and A. K. Urazgil'deeva, Dokl. Akad. Nauk SSSR, 174, 1359 (1967). 3. R.R. Shagidullin and T. E. Pavlova, Izv. Akad. Nauk SSSR, Ser. Khim., 2117 (1963), 995 (1965);

2091 (1966). 4. R.A. Nyquist, Spectrochim. Acta, 22, 1315 (1966). 5. F.S. Mortimer, Spectrochim. Acta, 9, 270 (1957). 6. F. Lallois, M. Durand, and I. P. Laurent, Compt. Rend., C263, 453 (1966); C264, 1005 (1967).

7. K.A. Jensen and P. H. Nielsen, Acta Chem. Scand., 17, 1875 (1963). 8. A. Merijanlan and R. Zingaro, Inorg. Chem., 5, 189 (1966). 9. C.N.R. Rao, J. R. Ramachandran, and A. Balasubramanian, Canad. J. Chem., 39, 171 (1961).

i0. R.R. Shagidullin, N. A. Chadaeva, N. I. Zarubina, and G. Kh. Kamai, Izv. Akad. Nauk SSSR, Ser.

Khim., 1543 (1966). ii. A.W. Reitz and R. Sabathy, Z. Phys. Chem., 41B, 151 (1938). 12. R.A. Zingaro, R. E. McGlathin, and R. M. Hedges, Trans. Faraday Soc., 59, 798 (1963). 13. A.N. Nesmeyanov, A. E. Borisov, and A. I. Borisova, Izv. AN SSSR Otd. Khim. N., 1199 (1962). 14. B.D. Chernokal'skii, S. S. Nasybullina, R. R. Shagidullin, I. A. Lamanova, and Gil'm Kamai, Izv.

Vyssh. Uchebn. Zavedeni[. Khimiya i Khim. Tekhnologii, 9, No. 5, 768 (1966).

* Not all the bands of the R and OR radicals are cited, but only the most characteristic and general for al l compounds con ta in ing them. In the f i r s t s e r i e s (for h y d r o c a r b o n r a d i c a l s R), the data a r e l imi t ed in view of the i n t e r f e r e n c e of the bands of the R and OR r a d i c a l s .

S u p e r i m p o s e d upon VAs = O"

1144