Infrared and Raman spectra of 1-cyclohexyl-3-methylurea and its related compounds

Press,1976. Printedin SorthernIreland Spectrochimica Acta, Vol. 328, pp. 1105to 1112. Pergsmon

Infrared and Raman spectra of l-cyclohexyl-3-methylurea and its related compounds YOSEIYUEI MID0 Department of Chemistry, Faculty of Science, Kobe University, Nada, Kobe 657, Japan (Received 28 Pebruay

1975; revised 1 October 1976)

of C,H,,NHCONHCH, and Abstract-The i.r. and Raman spectra (4000-100 cm-r) C,H,,NHCONHCD,, and their N-d compounds are given in the solid state. Also, the i.r. spectra (4000-400 cm-r) of some C,H,,NHCONHR type compounds (cHIJR) are presented. The vibrational assignments are proposed on the basis of comparisons among their vibrational spectra. The solution spectra of cHUR are studied with the aims of confirming the correlation between the N-H stretching frequency and the type of R group, and of determining whether or not rotational isomers can coexist by the bulkiness of the R group. INTRODUCTION

ground of the amide group [3].

Several workers have studied

the i.r. spectra

N,N’-disubstituted

RAO et al. studied

ureas [l-5].

the solution spectra of some dialkylureas dialkylthioureas and s-DtBTU considerably respsctively).

[S], and concluded with

bulky

groups

in the cis rotamer These

special attention

studies

of

that s-DtBU in CHCl,

(-75

have

are

and 45 %, aroused

our

I on the trams-planar -C-N-

struc-

II 0 of N,N’-disubstituted state

[7, S] and

from

the extensive

studied the i.r. spectra

alkyl

ureas

in solutions

form and pointed

R

in

[9-111.

examinations,

cluded that they are dominantly

the

solid

However,

we have

con-

in the tram-tram

out that the interpretation

/

H

H

I N

I N

\/

by

\

CH,

(CHUM-d,),

are studied as continuation

CHsNHCONH-

with

bulky

groups.

structure in CHUM [l]. the i.r. spectra

(s-DcHU)

on

the

BOIVIN band

(CHUM-ds), and

of

STEWART of sym-

protonating

hereafter),

C&H,,-

C,H,,NHCONHCDJ

C,H,,NDCONDCD,

are shown in Figs. l-4.

of our work

an i.r. characteristic

and MUENSTER studied dicyclohexylurea

(referred to as CHUM-d,

NDCONDCH,

In this paper, various I-cyclohexyl-3-alkylureas,

found

of CHUM

The i.r. and Raman spectra of C,H,,NHCONH-

RAO et al. is questionable.

on the derivatives

Various cHUR used were prepared by adding cyclohexyl isocyanate to the corresponding alkylamines (for CD, compound of CHUM to CD,NH, from its hydrochloride salt) [S]. These crude samples were repeatedly purified by recrystallization from suitable solvents. All the samples gave white powder crystals. The melting points, the analytical data, and the solvents for recrystallization of these samples are summarized in Table 1. The N-deuteration of CHUM was done by the previous methods [7, 81. The i.r. spectra were studied as KBr disks and Nujol mulls, and 10e3M Ccl, solutions. The spectra were recorded on a Hitachi EPI-G2 (4000-400 cm-l), a Perkin-Elmer 621 (700-300 cm-r) and a Hitachi 070 Michelson type (360-100 cm-i) spectrophotometer. The Reman spectra of powdered CHUM were observed by a JEOL S-l Raman spectrometer equipped with an Ar+ ion laser.

(1) Infrared and Ranaan qx&ra

R’

tram-tram

and BOMN

EEPERDkIENTAL

EESULTS AED DISCUSSIOE

II 0

cHUR,

reports on

cerning to the derivatives containing any of cyclo-

to the steric effect of such bulky

ture. We havesystematically

Any

data have not seen yet con-

hexyl groups.

[4] and

H substituents

both i.r. and Reman

(cHUM-d,)

Their vibrational

assign-

ments are tabulated in Table 2. The i.r. spectrum of CHUM-do (4000-760

is in accordance

cm-l)

with the spectrum

reported by Born

and BOIYIN

PI. Amide characteristic bands. CHUM-d,, and CHUMd3 have i.r. bands which shift on N-deuteration

1106

YOSHIYU~I MIDO

1106

Table 1. Melting point, analytical data, and solvents C,H,,NHCOKHR R

M.p.

CHUB

CH,-

(“C)

CHUM

C,H,-

cHUE

n-C,H,-

cHUP

i-C,Hg

cHUiB

a-C,H,--

cHUsB

160-161.5

I-C,H,-

cHUtB

190 -

cHUiP

rr-C,H,-

Lit. *

165.2-156.5 (167-158) 106.5 97.5-98 (106-7) 150-161.5 (152-163) 108-110 (115-116.5) 168

&C,H,-

Analysis

CHUB

Oba. Calc. Obs. Calc. Obs. Calc. Obs. Calc. Obs. Calc. Obs. C81C. Obs. Calo. Obs. Calc.

a

b c b

subl.

Solvent

C( %)

H(%)

N(%)

61.40 61.60 63.66 63.49 65.20 66.18 65.25 66.18 66.74 66.62 66.70 66.62 66.68 66.62 66.88 66.62

10.18 10.32 10.61 10.66 10.64 10.94 10.91 10.94 10.97 11.18 11.14 11.18 11.06 11.18 11.20 11.18

17.73 17.93 16.25 16.46 16.29 15.20 15.30 16.20 13.86 14.13 13.97 14.13 14.04 14.13 14.15 14.13

water dil. ethanol pet. ether ether ether DMF-water water DMF-water

* (a) J. L. BOIVIN and P. A. BOIVIN, Can. J. Chem., 29,478 (1951). (b) P. ADAMS, U.S. Patent. 3,161,676; Chem. Abst., BZ,P9023h (1965). (c) J. C. JOCHIMS,Chem. Ber., 98,212s (1966).

from

ca. 3340,

1580,

1490 and 490 cm-‘,

and 660 cm-l respectively.

to co. 2470,

One or two of

6N-C=

0)

bands appear

co. 620 cm-i,

respectively,

five bands, which on N-deuteration

decrease their

CHUM-~,,

and the

amide

intensities,

region should

1610

co.

cm-l,

in the

be the amide III

1320-1240 bands

cm-1

(mainly

6N-H).

are some bands which, on N-deuteration, newly region. Raman

or become

strongly

There appear

line

being

strong

as expected,

can

and t’hc amide IV

I’

and

IV’

bands

respectively,

and CHUM-~,.

at

for both

It should be noted that

but

not

on C-deuteration

of the

methyl group. In

be

stretching mode.

The amide I (mainly vC=O)

CHUM-~,

600

at 1624 and

the slight shift of both amide bands arises only on N-deuteration

in the 1050-950cm-1

A band near 1000 cm-r, the corresponding

associated with a sync C-N

and

strongly

for both CHUM-~,, and

bands,

the Raman and

However,

spectra,

YN-H

retain

amide

moderate

I and IV intensities.

the other amide bands do not appear

I

Fig. 1. Infrared spectra of CHUM-~, (-

the

I

) and CHUM-~, (- - - - -).

Infrared and Ramen speotraof I-cyolohexyl-3-methylurea,

c

m-l

Fig. 2. Infraredspeotraof CHUM-~, (-) as Raman lines. It is specially interesting that, in contrast to secondary amides and various proteins [12], the amide III modes of CHUM do not appear as Raman lines, probably indicating the presence of 8 certain electrical di&renoe in the H

-C--N-

I

structure between them.

II

0

CH, group vibrations. By comparing the spectra of CHUM-~,, or CHUM-~, with those of CHUM-~, or

and o’EIUM-d,(-----).

CHUM-~,, the result indicates to be:reasonable for other alhylureas with methyl groups [7, 8, 13, 141. It should be pointed out that the 1412 cm-l band, which ~8s called as the characteristic b8nd of CH&EICONH- structure by BOIVIN and Borvrx [I], was quite attributable to the CH, group attached to the nitrogen atom. C&O?MD& group tibrattilze. In describing the assignments of the characteristic bands of cyclohexyl group, we will use a conventional cyclohexane notation under Cs, symmetry reported by WIBERG and &RAKE [16]. The selection rule of

LOO

(Fig. 3. R&manspectraof cHUikf-cZ6 18

1107

) and cHUEd-d,(- - - -).

1108

YOSHIYUKI

MIDO

Fig. 4. Raman spectra of CHUM-~, (-----) the assumed

C 2h symmetry

seems to contribute

and CHUM-~, (- - - -).

Amide

characteristic

to the intensities of the i.r. bands and Raman lines.

bands are plainly

For example,

positions

the Raman

line at ca. 800 cm-l

is

bands of cHUR.

distinguishable

and band-shapes.

It

The amide

from the bandshould

be noted

corre-

that CHUB exhibit the strong and sharp amide IV

sponding i.r. band is very weak.

This line Landband the yll mode of A, species

band in contrast with dialkylureas.

are associated

frequencies seem to be sensitive to the number of

very

strong

and

with

(Ring vibration active).

[12&l, Raman

The medium

weak Raman A,

characteristic,

but

the

active but i.r. in-

i.r. band at 887 cm-l

(the

line) is assigned to the vs3 mode of

Some other bands. and

Raman

spectra in the 600-

region exhibit two medium lines at 463

320 cm-l.

The

GN-C-N

vibration

pected to appear as a strong Raman region.

MMU

strong Raman tively,

[13] and s-DMU

is ex-

line in this

[16] exhibit only a

line at 519 and 514 cm-l,

respec-

and these lines have been assigned to the

GN-C-N

vibration.

The bands

near 320 and

200 cm-1 may beassociated with the two W-N-C’ modes from the previous alysis of s-DMU.

normal

More detailed and extensive on not

an-

A strong i.r. band at 377 cm-l

may be assigned to GN-C’-C required

coordinate

only

skeletal

disubureas--s-DMU-ds:

DMU:

604 cm-l,

spectra

investigations motions

of other CHUB

The i.r. data for other cHUR

In analogy

but

are also

and s-DcHU

and s-DcHU

presented in Table 3, with our assignments.

are

ca.

660

622 cm-r, acu. 620 cm-r, s-DcHU:

CHUB:

tetrasuburea-TeMU:

581 cm-1

with the case of secondary

[17]. amide

[18], we have concluded from the positions of the amide I-III

bands that alkylureas

state are dominantly

clusion was confirmed

by the normal

analyses for the trans model of MMU of s-DMU

in the solid

in the trans form.

Our concoordinate

[13, 141 and

[7], and was supported by the study of

partially deuterated ureas [ 191. Therefore,

we might

conclude,

from

the

fact

that the amide II band appears specially in the 1580-1564

cm-r

region,

nantly in the trans-trans

mode.

torsions in this region. (2) Infrared

monosubureas-MAU:

;

cm-l, 642 cm-l,

species.

200 cm-l

substituents

The amide IV

Allcyl

group

relations

that

cHUR

exist

domi-

form.

vibration.

The

[S], derived previously

alkyl-group

cor-

on the basis of

structural points, were almost directly applicable, though

there

were some

bands.

The

assignments

vibrations

are compatible

The band near 1440 cm-l cHUR

overlappings for

to

cyclohexyl

other group

with those of CHUM. splits into two bands in

with a aec- or tert-alkyl group.

The bands

Infrared and Raman spectra of I-cyolohexyl-3.methylurea

1109

Table 2. Infrared and Raman spectra of I-cyalohexyl-3-methylureas (CHUM) C~H,rNHCONHCH, cHUM-d, i.r. Raman 3339 s* 3322 sh 3160 vw

3343 m*

2940 8

2946 vs

2868 s 2672 vw

2900 8 2960 vs 2672 vw

1624 1684 1627 1474 1447 1412 1370 1342 1316 1308 1273 1268 1243 1184 1160

s 8 sh w m m w w a m 8 8 s m m

1628 m 1640 1470 1448 1422 1378 1362

vw.b vw s w w w

CBH,,NDCONDCH, CHUM-d, i.r. Raman

2936

s*

2856 8 2660 w 2472 s 2460 sh

1609 s 1497 8

1444 1403 1371 1345

8 8 m m

2942

vs*

2897 vs 2860 vs 2678 vw 2482 m

1614 m

1486 vw 1460 8 1417 w 1380 w 1364 m 1310 w

1308 w

1270 m 1200 m

1162 m

1257 w 1247 w 1189 w 1160 m 1152 sh

1081 m

1080 w

1078 m

1086 w

1049 VW

1057 1034 990 971

1046 vw 1019 w 1000 m

1062 1033 1011 986 947 931

982 VW 963 vw

1262 m 1190 m

w 8 8 w

920 vw

928 w

887 846 797 784 773 716 662 616 494 462

m w vw vw m vw s.b m vw vw

887 w 862 m 802 s

377 318 286 194 160

8 w m w m

726 w 623 w 501 VW 463 m 446 sh 374 w 320 m 294w 202 w

947 w 928 w 883 844 793 784 766 708 496 600

m w VW vw s vw s.b s

1160 m

w 8 m w m vw

897 w 866 m 802 8

C,HiiNHCONHCD, oHUM-d, i.r. Raman 3344 8’ 3322 sh 3140 w

3342 m*

2937 8

2946 2896 2860 2670

2865 s 2676 w

2260 sh 2217 w 2133 w 2076 m 1623 s 1680 s 1527 sh

w vw m sh w m w w

vN-H Amide I + II

“8 vs vs VW

2226 w 2140 m 2086 m 1624 m

2935

s*

2866 s 2486 s 2460 s 2266 w 2220 w 2130 w 2080 m 1607 s 1490 s

2962 vs* 2900 8 2863 vs 2676 vw 2498 w 2460 m 2267 w 2238 w 2140 m 2086 m 1608 m

1447 8

1447 sh

1448 8

1370 w 1347 w 1318 8 1308 m 1275 m 1260 s 1246 m 1191 vw

1377 w 1364 m

1370 m 1348 m

1381 w 1366 m

1166 1125 1086 1074 1062

VW m m w w

970 vw

904 893 847 799 791 776

vw m w vw w w s.b 8 w w

370 308 276 197 149

8 m m w 8

1

YC-H§

I

vN-D

I

Yc-D Amide I, I’ Amide II, II’ 2 x Amide VI

a,CH,

i VT?Vl89 v19

Amide III

1310 w

1310 w 1265 s 1196 m 1169 m 1127 w 1087 s 1067 w 1034 m 978 w

915 896 866 800

w w m 8

681 w 667 618 497 469

Assignment t $

I

1447 8

718 w 610 600 464 448 373 318 292 202

C,Hi,NDCONDCD, CHUM-d, i.r. Raman

620 500 464 460 370 310 283 200

w w m sh w m vw w

1260 w 1260 w 1190 w 1163 w 1126 m 1086 m 1075 sh 1052 vw 1026 m 1002 w 982 w 949 w

888 m 846 vw

770 670 490 600

8 w s.b s

VSO Amide III

1267 m 1200 w 1160 m 1134 vw 1086 m

%I3

vC'-N. WH,

vsl

VP

&CD,

1068 m 1034 8 1010 w 960 w

895 w 866 m 798 m

676 w 600 vw 496 vw 463 m 460 sh 368 w 307 m 286 vw 198 w

Amide III’ d,CH, a&D, VZ8 VI1 Vll V11 Amide VI, VI’ ? Amide V, V’ Amide IV, IV’ r47 SN-C-N V11 GN-C’-C,

vl,

de--N--c' V25 W-N-C’

* Intensity code: 8, strong; m, medium; w, weak; v, very; sh, shoulder; b, broad. t Notation: v, stretching; 6, deformation; 6,, rocking. $ Numbered v denotes the assignment only for cyclohexyl group. We assumed cyolohexyl group under C, symmetry based on the study by WIBERQ and SERAICE[16]. 5 They inolude both vC--H bands of cyclohexyl and methyl groups in cHUMdo and cHUM-d,, but those of only the former group in cHTJM-d, and CHUM-d,. 7 The i.r. spectra in this region were not measured.

1110

YOS~YKLKI MIDO Table 3. Infrared spectra of cHUR (C,H,,NHCONHR)

e-DcBIJ

cBSJE

1624 s* 1674 8 1536 sb

1626 1684 1630 1476

s+ s sh w

CHUP 1626 1680 1627 1480

s* s sh m

5

oBIJ?P

CBIJB

oBUiB

CHu8B

oHUtB

1626 s+ 1676 s 1630 sh

1628 s* 1576 s 1630 sh 1480 w

1626 s* 1672 s 1627 sb

1630 s* 1670 s 1627 sh

1462 m 1442 m 1377 w 1348 w 1310 8

1466 s 1440 s 1386 m 1367 m 1346 w 13118

1630 s* 1664 s 1530 sh 1474 w 1460 sh 1447 s ? 1388 m 1361 s 1350 VW 1318 s

Assignment Amide I Amide II 2xAmideVI S,CH,, 6CH, 1 VI, “6. I“17. V&1

1443 m 1379 m

1468 m 1446 m 1376 w

1349 w 1316 8

1360 VW 1311s

1349 VW 1318 s

1463 m 1445 m 1436 m 1380 m 1363 s 1348 VW 1322 s

1274 m

12’73 s

1271 s

1304 m 1270 s

1273 s

1270 s

1308 s 1277 s

1318 s 1280 s

1246 s 1232 m

1263 s 1238 s

1266 s 1236 s

1247 s 1234 s

1260 8 1234 s

1249 s 1232 s

12618 1234 s

1186 w 1158 w

1189 w 1157 m

1183 w 1166 w

1196 1160 1139 1127 1093

m m m m VW

1184 w 1156 w

1181 w 1160 m

1114 VW

1127 w

1187 1163 1140 1111 1093

1260 m 1248 m 1240, 1218 m 1188 VW 1155 m

1069 s 1048 VW 1028 VW

1081 s 1047 w 1028 w

1447 m 1434 m

1138 VW

1080 s 1048 w 1031 w

1088 s 1068 w 1046 w

1084 s 1047 VW 1028 VW 1016 VW

982

966

VW

966 VW

966 VW

967

893 8

916 w 893 s

910 w 891 s

842 810 793 768 660 606 492 452 418

841 760 800 770 647 619 606 466 420

843 w 803 VW 7 655 s.sh 642 8 537 w 447 VW 417 w

w VW VW w s.b s VW VW vw

982

VW

VW

963 w

VW

VW m VW sh s.b s w “w w

914 890 854 840

VW s m w

763 660 600 497 447 415

w s.b s VW VW w

sh 890 s

900

845 736 800 769 660 620 507 440

VW VW vw vw s.b s VW VW

1460 sh 1447 8 1438 sh 1376 w 1340 w

w w m w VW

1064 s 1060 VW 1028 VW

1023 sh 960 w

998 w

970

948 VW 920 w 891 s 823 VW 842 w

967

940 w

800 767 662 620 508 440

VW m s.b s w w

6,CH,, 6CH, V?Y“18, v19 Amide III VOO Amide III V.9 “10 &!H, UC-C UC’-N, VP

I

WHo

WH,

VW

924w

920

891 m 780 w 848 w

891 s 784 sh 846 VW

798 VW 767 w 660 s.b 600 m s 7

800 776 647 698 504 460 426

UC-C v,C-N

U-W

VW

VW w s.b m VW w w

Vlll Subs. sens. V14 6,CH, (chein)

vnt

1050,

1030 and

600 cm-l

shift

slightly

in

other primary

alkyl

groups,

30

Amide VI Amide V Amide IV 2.L-N GN-C’-C, IX-C-C

*,t,$ See the footnotes in Table 2 for Intensity code,* Notation,t Numbered v.$ 5 UN-H and UC-H bands in the 3600-2800 cm-i region are omitted in this table, but UN-H are listed in Table 4. near

us1

UC-C

1090 “W 1077 sh 1070 m 1060 w 1030 “w

1078 s 1047 w 1029 w

VW

I

frequencies

while

s-DAU

with

branched alkyl groups have the lowest frequency

6-DcHU.

band [9. lo]. (3) N-H

stretching absorptions

Table 4 shows the data, for the N-H

For the case of cHUR, it is worthwhile to examine the

applicability

between

free

of

N-H

types of substituents; frequency slightly

bend,

our

established

stretching s-DMU

s-DiBU

higher frequency

and

shows the highest-

exhibits than

correlation

frequencies a band

8-DAU

at a

with the

stretching

absorptions of cHUR in the low3 M solutions. We will conventionally classify cHUR into three cHUR-A: CHUM and aHUiB (showing groups; two bands), cHUR-B: cHUE, cHUP and CHUB (a band near 3445 cm-l), and cHUR-C: cHUiP, cHUeB and oHUtB (a band at 3436 cm-l).

1111

Infrared and Raman spectra of I-oyolohexyl-3-methylurea Table 4. The N-H

stretching absorptions of I-oyolohexyl-3-alkylureas (C,H,,NHCONHR) Solid (KBr disk)

Solution (0.001 M, Ccl,) O.D.

Frequency (cm-l)

Compound

3457 (3460

CHUM

3433 3434) *

CHUP oHUiP CHUB cHUiB cHUsB cHUtB s-DoHU $

3339

3322

0.43

31

3353

3317

0.40

34

3351

3311

24

0.44

3330

34

3341

3324t

-_t

37

3343

3325t

0.43

25

0.42

23

0.38 0.38

Frequency (am-‘)

-

0.26

0.48

3446 (3445) * 3446 (3447)* 3436 (3439) * 3446 (3446) * 3460 3436t (3447) * 3436 (3439)* 3436 (3471: 3436)* (3436)*

OBSJE

Y+ (cm-i)

3325 3357

3336

* 0.05 M CHCl, solution, except for s-DcHU (saturation). t Shoulder band. $ Weak band corresponding to the 3469 cm-r band in s-DtBU, see text. 8 Unfortunately, the Ccl, solution spectrum could not be measured, owing to the very low solubility. In

connection

with

our correlation

it can be

tion at a position and with an 0. D. characteristic

understood that the two bands of CHUM (cHUR-A)

of the substituent

result from two different types of N-H

The frequency

the higher component

resulting

from

groups;

the methyl

the N-H

attached

and

O.D.

to the N-H

value

tively, than those of other alkyl group.

ponent

absorption

the

N-H

group

attaching

In the cases of CHUB-B

hexyl group.

it can be also understood

that

overlap

each

absorptions

other

and cHUR-C,

two components

from two different types of N-H closer than those of cHUR-A

cyclo-

groups may be

(cHUR-B),

(cHUR-C),

thus

or quite the

from such two components

as only one band at the mean position of the two. The (O.D.)

data

for the

optical

cHUR-C

while the half-intensity

widths

group attaching weaker

that

alkyl group is rela-

from

the N-H

attaohing an other alkyl group [ll], the

O.D.

of cHUR-C

group

it is deduced

is enhanced

without

widening its vt, while the vt of cHUR-B without enhancing its O.D. the

two

components

of

; an N-H

dependently

widen

This may mean that cHUR-C

other and those of cHUR-B agreement

of

From

absorption from the N-H

a branched than

and

(vi)

are smaller than those of cHUR-B.

the fact that the N-H

that

densities

show similar values between cHUR-B

oHUR-C,

tively

apparent

bond

a peculiar N-H

overlap

each

are in a slight disin cHUR stretching

gives inabsorp-

The N-H

of the cyolohexyl

group

to appear at a similar position

with a similar O.D. (the lowest

to those

of branched

frequency

and

the

and alkyl

smallest

0. D. value). Using

N-H

appearing

characteristic

is concluded groups

of

group are higher and larger, respec-

group attaching methyl group, and the lower comfrom

bond.

characteristic

similar cHUtB cm-l,

CHCl,

as a solvent,

behaviors

to

those

we observed in

Ccl,.

also

However,

exhibits a new but weak shoulder at 3471 corresponding

3469 cm-l

of a-DtBU

clude that

to the questionable in Ccl,

the previous

applicable

to cHUR

amined cHUR

[9].

We

trans-correlation

band at can conis also

and that in the solution ex-

are dominantly

in the trans-trane

form, though there are also two rotational isomers of cHUtB

in CHCl, [lo].

The

bands

N-H

observed

in the solid state

seem to roughly follow such a correlation as observed

in solutions,

bonding on the N-H that the quantitative

but

the

effect of hydrogen

absorptions may be so large aspects are quite complicated.

Acknowledgements-The author wishes to express his deep gratitude to Dr. K. MACHIDA for his valuable comments and suggestions and to Dr. Y. SAITO of

1112

Y0snrYuK1 MID0

Kyoto University for the measurements of the Ram&n spectra. Thanks 8re also due to Miss S. NISHINAKAfor her elemental analyses of CHUB. This work was supported by grants from the Ministry of Eduoation of Japan.

REFEREECES [l] J. L. Borvxn and P. A. BOIVIN, Can. J. Chem., 22, 661 (1964). [2] H. J. BECKERand F. GRIFFEL,Naiurzuissenachaften, 45,467 (1956). [3] R. STEWAIZTand L. J. MUENSTER,Can. J. Chem. 89, 401 (1961). [4] C. N. R. RAO, G. C. CEATU~VEDI and R. K. GOSAVI,J. Mol. Spectroscopy, 28, 626 (1966). [S] C. I. JOSE, Spectrochim. Acta, 25A, 111 (1969). [6] R. K. GOSAVI, U. AQ~U~WALA and C. N. R. RAO, J. Am. Chem. Sot., 89,235 (1967). [7] Y. MIDO and H. MURATA, Bull. Chem. Sot. Japan, 42,3372 (1969).

[S] [9] [lo] [ll] [12]

Y. MIDO, Spectrochim. Acta, 28A, 1503 (1972). Y. MIDO, Spectrochim. Acta, 29A, 1 (1973). Y. MIDO, Spectrochim. Acta, 29A, 431 (1973). Y. MIDO, Bull. Chem. Sot. Japan, 47, 1833 (1974) (E) S. K. FREEMAN,AppZiuztions of Laser Raman Spectroscopy, John Wiley, New York, 1974. (b) M. C. TOBIN, Lacer Raman Spectroawpy, John Wiley, New York, 1971. [13] Y. SAITO,.I(. MACHIDA and T. UNO, Spectrochim Acta, SlA, 1237 (1976). [14] Y. MIDO and H. MURATA, J. Chem. Sot. Japan (Nippon Kagaku .%sshi), 90,264 (1969). [16] K. B. WIBER~ and A. SIX~AKE,Spectrochim. Acta. 29A, 667 (1973). [16] Y. MIDO, unpublished data. [17] H. L. SPELL and J. LAANE, Spectrochim. Acta, 28A, 296 (1972). [IS] T. MIYAZAWA, T. SHIMA.NOUCHI and S. MIZVSFIIMA,J. Chem. phys., 24, 408 (1956); 29, 611 (1958). 1193 Y. SAITO, K. MACHIDAand T. UNO, Spectrochim. Actu, 27A, 991 (1971).