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Phosphorescence spectra of benzonitrile and related compounds
Spectrochiiica Acta,
1962,
Vol. 18,
pp.1201to 1216.Pergamon Press Ltd.Printed inNorthern Ireland
Phosphorescence spectra of benzonitrile and related compounds KUNIO TAKEI* and YOSHIYA KANDA Department of Chemistry, Faculty of Science, Kyushu University, Fukuoke, Japan (Received
2 Februaq
1962)
Abstract-The phosphorescence spectra of benzonitrile, o- and p-dioyanobenzenes and o-, mand p-tohmitriles have been studied in ethanol and in cyclohexane at liquid sir temperature. Benzonitrile in ethanol gives a sharp spectrum beginning at 26,910 cm-l, and an even sharper one in cyclohexane beginning at 26,780 cm- l. Conversely, the spectra of o- and p-dicyanobenxenes in ethanol are sharper than those in cyclohexane. The 0,0-band of the spectrum of the o-isomer has been found at 25,440 cm-l in ethanol and 25,340 cm-l in cyclohexrtne, and that of the p-isomer at 24,670 cm-r in ethanol and 24,560 cm-l in cyclohexane. The general appearance of the spectra, of o-, m- and p-tolunitriles is quite similar to one another, and the structure resembles that of the dicyanobenzene spectra. Vibrational analyses of these spectra are discussed. INTRODUCTION KOWALSKI
[l]
found ten phosphorescence
bands of benzonitrile
between
371 m,u
(26,950 cm-l) and 451 rnp (22,170 cm-l) in 1912. LEWIS and KASHA [2] reported the triplet-singlet emission of benzonitrile in EPA at 90°K and assigned a strong band at 27,000 cm-l to the O,O-band of the system. HIRT and HOWE [3] investigated the ultraviolet absorption spectrum of benzonitrile. BASS [4] studied the fluorescence spectrum of benzonitrile vapour. They performed successful analyses of the spectra and concluded that the electronic transition of benzonitrile is Al---B, in analogy to the SPONER and WOLLMAN [5] treatment of monochlorobenzene. Benzonitrile has been investigated in the Rnman effect [6] and in infra-red absorption [7]. Recently GREEN [8] studied the Raman shifts of benzonitrile and assigned the vibrational spectra. On the other hand, no data has been reported on the triplet-singlet emission of o- and p-dicyanobenzenes and o-, m- and p-tolunitriles. We studied the triplet-singlet spectra of benzonitrile, o- and p-isomers of dicyanobenzenes, and o-, m- and p-isomers of tolunitrile. Raman, infra-red, and ultraviolet spectra of those compounds were also studied. Their vibrational analyses will be discussed. * Present address: Department of Engineering Chemistry, Faculty of Engineering, Miyazaki University, Miyazaki, Japan. [l] [2] [3] [4] [5] [6]
J. VON Kowtisxr, Physik. 2. 12, 956 (1912). G. N. LEWIS and M. KAS~, J. Am. Chem. Sot. 66, 2100 (1943). R. C. HIRT and J. P. HOWE, J. Chem. Phys. 16, 480 (1948). A. M. BASS, J. Chem. Phys. 18, 1403 (1950). H. SPONER and S. WOLLMAN, J. Chem. Phy8. 9,816 (1941). L. SIMONS,Sot.Sci.Fennica, Comment&ones Phy. Math. 6,13 (1932). K. W. F. KOHLRAUSCH end A. PONGRATZ, Sitzber. Akad. Wiss. Wien 142,637 (1933); Monatsh. Chem. 63,427 (1937). [7] J. LECOMTE, J. Phys. radium 8, 489 (1937). [S] J. H. S. GREEN, Spectrochim. Acta 17, 607 (1961). 1201
KUNIOTAKEIand YOSHIYAKANDA
1202
EXPERIMENTAL Benzonitrile and o-dicyanobenzene were obtained from Tokyo Kasei Co. Benzonitrile was washed with a sodium carbonate solution in order to remove benzoic acid. It was then dissolved in ether, washed with water and dried with calcium chloride. The solution was filtered and ether was removed by distillation. The residue was fractionally distilled twice under reduced pressure. o-Dicyanobenzene was sublimed twice under reduced pressure, recrystallized from acetone and dried at 100°C for 1 hr. The melting point was 161*5”C. p-Dicyanobenzene was obtained from Dozin Chemical Institute, Kumamoto, Japan. The melting point was 222°C. It was warmed under reduced pressure in order to remove a trace of benzene. Three isomers of tolunitriles were obtained from Tokyo Kasei Co. They were carefully distilled under reduced pressure. Ethanol and cyclohexane were purified in the same way as that reported previously [9]. The purified benzonitrile, o- and p-dicyanobenzenes and tolunitriles were dissolved in ethanol and in cyclohexane at the concentration of 1O-2 or 10es mole/l. The phosphorescence cell, the phosphoroscope and other apparatus used in this work were the same as those reported previously [9]. RESULTS AND DISCUSSION (a) Benxonitrile The phosphorescence spectrum of benzonitrile was observed in ethanol and cyclohexane at 90°K. Microphotometer tracings are shown in Fig. 1 and the spectral data are given in Table 1. The general appearance of the spectra of benzonitrile resembles Table In ethanol
1. Phosphorescence In cyclohexane ___
1w3 mole/l.
__~ Wave number
Intensity
AG
26,910 26,460 26,150
9 4 6
0 450 760
25,740 25,310 24,990
8 9 8
1170 1600 1920
24,590
8
2320
24,150 23,710 23,400
9 8 7
2760 3200 3510
22,990
8
3920
22 560 221110 21,450
7 6 4
4350 4800 5460
[Q] Y. KANDA
spectra
Wave number 26,780 26,315 26,010 25,790 25,600 25,175 24,820 24,590 24,410 24,180 24,000 23,580 23,230 22,970 22,800 22,570 22,400 21,940 21,380 20,830
of benzonitrile
at 90°K
low3 mole/l.
Intensity 9 5 7 8 9 9 8 8 8 9 9 8 8 7 7 7 7 6 5 5
and R. SHIMADA, Spectrochim. Acta
Av” 0 465 770 990 1180 1605 1960 2190 2370 2600 2780 3200 3550 3810 3980 4210 4380 4840 5400 5950
Analysis o-o 0 - 460 0 - 765 0 - 998 0 - 1178 0 - 1597 0 - 1178 0 - 1178 0 - 1178 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597
15, 211 (1959);
x x x x x x x
765 998 2 998 1178 2 1178 1178 1178 2 2 3 2 3 -
17, 1 (1961).
- 765 - 998 x 2 998 1178 1178 1178
998
Phosphorescence spectra of benzonitrile and related compounds
20000 Fig. 1. Phosphorescence 1 1’ 2 2’ 3 3’
22000
24000
26000
1203
26000
spectra of benzonitrile and related compounds at 90°K.
. . . benzonitrile in ethanol . . . benzonitrile in cyclohexane . . . o-dicyanobenzene in ethanol . . . o-dicyanobenzene in cyclohexane . . . p-dicyanobenzene in ethanol . . . p-dicyanobenzene in cyclohexane
those of o- and p-dicyanobenzenes. The spectrum of benzonitrile in cyclohexane gave a very fine structure. The lifetime of the phosphorescence in ethanol was visually estimated to be about 3 set and that in cyclohexane about 2. The phosphorescence in ethanol was a strong violet, and the exposure time was 2 hr with a slit width of 100 ,Uand Eastman Kodak Tri-X film. The phosphorescence in cyclohexane was weak violet and the exposure time ranged from 7 to 10 hr. Fourteen bands were found in the ethanol spectrum. KOWALSKI [I] found ten bands between 26,950 and 22,170 cm-l. LEWIS and KASHA [2] found the O,O-band at 27,000 cm-l. We found that the O,O-band lay at 26,910 cm-l. HIRT and HOWE [3] found the O,O-band at 36,516 cm-l in the ultraviolet absorption spectrum of benzonitrile. The S’-T difference in frequency is 9606 cm-l. This value seems reasonable for the S-T separation of n--r * type. A very weak band was found at 26,460 cm-l separated by 450 cm-l from the O,O-band to the longer wavelengths. The difference frequency may be assigned to the Raman vibration of 460 cm-l. This vibration is a moderately strong band in the Raman spectrum but does not appear in infra-red spectrum. It may be assumed to be a totally symmetric vibration. The next prominent band is a band of medium intensity with a frequency of 760 cm-l. The frequency appears in multiples and combinations with the 1600 cm-l progression and indicates that it is a totally symmetric vibration. In the fluorescence spectrum of benzonitrile BASS [4] found a frequency of 771 cm-1 and assumed it to correspond to
1204
KUNIO TAKEIand
YOSHIYA
KANDA
Table 2. Ground-state vibration frequenciesin benzonitrile Ramcln effect
KOHLRAUSCH
HIRT and HOWE
WI
131
170 ((lb, O&T)
170 (10)
381 (2, 0.36)
378 (3)
460 (6) 549 (6) 024 (5, 0.84)
460 (6) 548 (5) 623 (5)
Tnfra-red absorption
GREEN
181
LECOMTE
PI
172 (m) dp 320 (VW) 381 (w) dp 405 (TV) 460 (8) P 549 (8) dp 624 (m) dp 650 (w)
0.15
762 (4) 764 (6)
751 (m) P 765 (m) P
K48 616
922
1001 (10) 1026 (3)
997 (4 P 1023 (m) p
1178 (8, 0.24)
1178
1178 (s) dp
1190 (8)
1102
1190 (8) p
462t 548t 624 (w) 660 (VW) 675 (ah) 687 (s) 701 (ah)
1002
1310 (w)
1353 (0)
1353 (w)
1447 (1)
1445 (w) dp
1391 (In) 1443 (s)
1493 (2)
1498 (m)
1486 (8)
1598 (10)
1600 (8) dp
1131
542 (8)
MASAKI
WI
469 547 616
HLRT and HOWE
r3i
Fluorescenoe -~
BASS
M
170 269 314 380
173 270 314 382
462 548 626
462 548 618
Phosphoresce*ce
This research
465
670 687 (10)
768 (8) 756 (10) 798 (ah) 844 (w) 888 (ah) 889 (ah) 926 (8) 921 (4) 068 (VW) 987 (VW) 1001 (m) 1020 (4) 1026 (8) 1028 (4) 1032 (4) 1060 (3) 1071 (5) 1072 (3) 1098 (m) 1163 (8) 1151 (0) 1171 (1) 1176 (8) 1176 (1) 1183 (1) 1192 (s) 1216 (sh) 1275 (2) 1287 (8) 1282 (2) 1312 (w) 1323 (0) 1333 (m) 1335 (0)
1310 (1)
1597 (IO, 0+38)
MIWXE
681
754
838
998 (15, 0.04) 1023 (3)
iSI
208* 263* 313* 383*
616 686 761 (3) 765 (5)
GREEN
UV absorption
1440 (5) 1461 (5) 1486 (7) 1492 (7) 1497 (7)
1520 (VW) 1670 (ah) 1577 (In) 1595 (8) 1585 (3) 1681 (w) 1667 (1) 1715 (w) 1745 (1) 1761 (w) 1812 (w) 1795 (2) 1894 (w) 1890 (2)
1009
141 773
(751) 771
841
845
1003 1026
1176
770
990
1180
1194
1311 (1349)
1498
1603
1605
1205
Phosphorescence spectra of benzonitrile and related compounds Table 2. (Co&d) Infra-red absorption
Ramm effect
WV absorption
KOELRAU~C~
HIRT and HOWE
GREEN
LECOMTE
GREEN
MECKE
[‘A
[31
PI
[71
PI
[I31
2224 (lob, 0.23) 3071 (Sb, 0.30) 3146 (1) 3196 (1)
2229 (10) 3071 (8)
2222 (8) p
1961 (w) 2222 (8) 3039 (8)
MASAKI
v41
Flumes- Phosphorcence escenoe ______
HIECT and HOWE
BASS
[31
[41
1967 (2) 2222 (5) 3039 (7)
This research
(2228)
3071 (8) p
* Values from BARCHEWITZ and PARODI [15]. t Values from MECKE [13].
C-CN bond vibration. It is, therefore, assumed that the frequency 760 cm-1 The next prominent band, the third corresponds to the C-CN bond vibration. strongest in the spectrum, is at 1170 cm-i from the O,O-band and may be assigned to the Raman vibration of 1178 cm- l. This is the strongest line in the Raman spectrum and has a depolarization factor of 0.24. It may also be a totally symmetric vibration. This frequency 1170 cm-l also occurs in overtones up to the third and in combination with a progression of 1600 cm-l. The vibrational frequency of 1600 cm-l of benzonitrile concerns the second strongest band in ethanol and assigned to the totally symmetrical Raman line of strong intensity at 1597 cm-l. This frequency forms a main progression of the spectrum in ethanol. Twenty bands were found in the spectrum in cyclohexane. The O,O-band lies at 26,780 cm-i which is shifted about 130 cm-l toward the red from the corresponding band in ethanol. The vibrations which appear strongly in the phosphorescence spectrum have the frequencies of 465, 770, 990, 1180 and 1605 cm-l. The spectral data are listed in Table 1. The analysis of the cyclohexane spectrum is shown at the last column in Table 1. The frequencies of 465, 770, 1180 and 1605 cm-l may be of totally symmetric vibrations by the same treatment as that of the spectrum in ethanol. The 990 cm-l frequency is assigned to the Raman frequency of 998 cm-l, which is the strongest line and corresponds to a ring vibration of 992 cm-l in benzene. It is noteworthy that the observed vibrational frequencies in cyclohexane are generally larger than the corresponding ones in ethanol. The fundamental ground state frequencies which were observed in the phosphorescence spectrum in cyclohexane are collected in Table 2 and compared with the value obtained through other methods by other workers. It might be assumed that the phosphorescence spectrum of benzonitrile is somewhat similar to that of toluene studied by KANDA and SPONER [lo]. However, the intensity of the O,O-band of the benzonitrile spectrum is relatively stronger than that of the toluene spectrum. This suggests that a CSN group resonates with a benzene nucleus and this resonance gives rise to stabilization also in the upper state. A similar phenomenon was found in the phosphorescence spectrum of biphenyl [ 101.
a,
[lo]
KANDA and H. SPONER, J. Chem. Phys. Y. SAKAI, Spectrochim. Acta 17, 1 (1961).
Y.
28, 798 (1958);
Y.
KANDA,
R.
SHINADA
and
1206
KUNIO TAKEI and YOSHIYA KANDA
Hnt~ and HOWE reported that the electronic transition of benzonitrile is lBp--lA,, its moment lying in the plane of the ring and perpendicular to the molecular axis. We assumed the molecular structure of benzonitrile at 90°K has also the same point group C,,. Therefore, the phospohrescence process must be of 3A, -+ lA,. (b) o-Dicyanobenzene The phospohrescence spectrum of o-dicyanobenzene was observed in ethanol and cyclohexane at 90°K. Microphotometer tracings are presented in Fig. 1 and the spectral data are listed in Table 3. The light emitted is a strong violet and the exposure time ranged from 2 h in ethanol to 10 hr in cyclohexane with a slit width of 100 ,u and Fuji special test plates. The lifetime was roughly estimated by visual observation to be about 2 s in ethanol and 1 s in cyclohexane. Ten bands were found between 25,440 and 21,710 cm-l in ethanol spectrum. A strong band lies at 25,440 cm-l and is assigned to the O,O-band of the spectrum. It Table 3. Phosphorescence spectra of o-dicyanobenzene In cyclohexane
In ethanol 10m3mole/l. Wave number
25,440 24,760 24,295 23,905 23,620 23,220 22,750 22,380 22,070 21,710
Intensity
8
AF 0
680 1145 1535 1820 2220 2690 3060 3370 3730
Wave number
at 90°K
10e2 mole/l. Analysis
Intensity
Ai;
25,340 25,190 24,640 24,180 23,775
7 7 9 10
150 700 1160 1565
23,070 22,630 22,240 21,920 21,530 21,090
9 9 8 8 7 5
2270 2710 3100 3420 3810 4250
9
0
o-o
0 0 0 0 0 0 0 0 0 0 0
-
172 705 1175 1590 1175 1590 1590 1590 1590 1590 1590
x x x
705 705 1175 2 1175 - 705 2 - 705 2 - 1175
lies at 1470 cm-l toward longer wavelengths from the O,O-band of benzonitrile in ethanol. A separation of 680 cm-l from O,O-band is barely found and is assigned to the Raman line at 705 cm-l (ai). A separation of 1145 cm-l is assigned to the Raman frequency of 1175 cm-l (ai). Both frequencies of 680 and 1145 cm-l appear in combination with the 0,0-band and with the 1535 cm-l progression throughout the spectrum. The 1535 cm-l frequency is assigned to a totally symmetric Raman frequency 1590 cm-r. We studied the Raman and infrared spectra of this compound and the results are The Raman spectrum given in the first and second columns in Table 5, respectively. was observed in an acetone solution and the infra-red spectrum was measured by the KBr disk method. The Eleven bands were found in the phosphorescence spectrum in cyclohexane. tracing curves are shown in Fig. 1 and the spectral analysis is listed in the last column in Table 3. The light emitted was weaker than that in ethanol. A band at 25,340 cm-l are ascribed to the O,O-band. A shoulder was found on the red side of the O,Oband and the separation was estimated to be 150 cm-l. We found Raman lines at
Phosphorescence
spectra
of benzonitrile
and related
1207
compounds
140 and 172 cm-l in the Raman spectrum of o-dicyanobenzene but it is uncertain whether the frequency of 150 cm-l in the phosphorescence spectrum should be assigned to the Raman line at 140cm-l or at 172cm- l. Other vibrational frequencies found in the phosphorescence spectrum in cyclohexane were 700, 1160 and 1565cm-l and they were assigned to Raman frequencies of 705, 1175 and 1590 cm-l, respectively. The frequency of 1590 cm-l was seen to form a main progression. The ultraviolet absorption spectrum of this compound was observed in ethanol, in n-hexane and in the vapour and the results are shown in Fig. 2 and Table 4. The
34000
Fig. 2. Ultraviolet 1
absorption
. . . in the vapour Table
In ethanol lop4 mole/l at 20°C
4. Ultraviolet
36000
36000
spectra of o-dicyanobenzene in ethanol, in n-hexane and in the vapour. 2’. . . in n-hexane 2 . . . in ethanol absorption
spectra
of o-dicyanobenzene.
Vapour at 70” N 90°C
In n-hexane lop3 mole/l at 20°C
Analysis Wave number
34,425
35,140
E
8600
7200
Wave number
A;
0
715
34,530
35,180
E
570
420
Wave number
A;
0
650
35,580
7900 1155
35,670
470
1140
36,325
6400 1900
36,380
360
1850
37,230
4900 2805
37,300
250
2770
34,780 34,820 34,855 34,895 35,450 35,490 35,525 35,570 35,740 35,780 35,820 35,865 36,010 36,050 36,090 36,520 36,750 37,095 37,275 37,700 37.956
Intensity w w
m m VW W W
m w W W
m w W
m W W W W W W
-~~ -115 -75 -40 0 555 595 630 675 845 895 925 970 1115 1155 1195 1625 1855 2200 2380 2805 3055
0-40x3 0-40x2 0 - 40 030 0,675 - 40 x 3 0,675 - 40 x 2 0,675 - 40 0,675 0,970 - 40 x 3 0,970 - 40 x 2 0,970 - 40 0,970 0,1195 - 40 x 2 0,1195 - 40 0,1195 0,675 + 970 0,675 + 1195 0,970 + 1195 0,1195 x 2 0,675 + 970 + 1195 0,675 + 1195 x 2
KUNIO TAKEI and YOSHIYAKANDA
1208
Table ci. ~ro~d-s~te Rwnan effect in acetone -._140 (4) 172 (2) 563 {Z) 612 (1) 663 (1) 705 (2)
984 (2) 1032 (4)
117.5(I) 1205 (6)
1296 (2)
1590 (3b)
2230 (Sb)
Infra-red absorption KBr disk
vibration frequencies in c-dicyanobenzene UT absorption Phosphorescence in cyclohexane in vapour ~--~ 150
666 VW b 702 m 768 vs 803 m 850 VW b 882 VW 904 w 922 w 939 YW 961 s 1030 VW 1052 VW 1078 VW b 1087 vw 1145 vw 1178 w 1186 VW 3202 8 1222 s 1245 w 1293 s 1347 VW 1400 w b 1447 s 1487 vs 1572 m 1590 s 1657 w b 1737 w b 1768 w 1847 w b 1885 w 1930 w 1968 w 1998 w 2232 vs 2338 w 2590 w 2630 w 2750 T 3032 m 3068 m 3090 111
678
700
970
Ilt95
1160
1565
symmetry
Phosphorescence spectra of benzonitrile and related compounds
1209
most prominent feature of the ultraviolet absorption spectrum of o-dicyanobenzene vapour is the group of bands culminating at a band at 34,895 cm-l in intensity with an extremely sharp edge on the ultraviolet side. This band is taken at the O,O-band. The general appearance of the spectrum is very similar to that of benzonitrile. Several bands on the red side of the O,O-band are attributed to difference due to socalled w-v transitions. The spacing of 40 cm-l and its multiples appear quite often in the ultraviolet spectrum. The same difference was also found in the absorption spectrum of benzonitrile vapour. The first major band appeared at 35,570 cm-l, distant by 675 cm-P to the ultraviolet side of the O,O-band. This frequency is assigned to a vibrational frequency of the upper state and corresponds to a Raman frequency of 705 cm-l (al). On the red side of this band several bands of spacing 40 cm-l were also found. Two strong bands were found at positions separated by 970 and 1195 cm-l from the O,O-band and accompanied by weaker bands to their red sides. The frequency of 970 cm-l is assigned to 1032 cm-l Raman vibration, which is attributed to the symmetric ring The frequency of 1195 cm-l is assigned to 1175 cm-l (al) breathing vibration. Raman vibration. Six bands are found on the ultraviolet side of the band at 36,090 cm-l (O-1195 cm-l). The spectral analyses of these bands are shown in Table 4. The absorption spectrum of o-dicyanobenzene in solution in ethanol is similar to that in n-hexane as shown in Fig. 2. The strong band at 34,425 cm-l in ethanol is assigned to the O,O-band of the system. The O,O-band in n-hexane, however, was observed at 34,530 cm-l. The spectrum in ethanol shows a red shift compared with that in n-hexane. Therefore, the singlet-singlet absorption system is of W-T* type and the same is deduced for the triplet-singlet emission. By analogy to the SPONER [5] treatment of o-dichlorobenzene, the electronic transition for o-dicyanobenzene is IA, +- IA,. The ground state vibrational frequencies of the o-isomer are listed in Table 5, where symmetry assignments are included. The lowest triplet state in benzene is B,,. If the symmetry is reduced from D,, to CZV,to which o-dicyanobenzene belongs, B,, in D,, goes over to B,. Therefore, the lowest triplet of o-dicyanobenzene in a B, level and the triplet-singlet emission has a transition moment along the y axis. The y axis is taken along the perpendicular direction to the molecular axis in the plane. The transition 3B, -+ l.4, is then allowed by symmetry but forbidden by spin multiplicity. The vibrational analyses of the phosphorescence spectra conform with these symmetry properties. (c) p-Die yanobenzene The phosphorescence spectrum of p-dicyanobenzene was studied in ethanol, carbon tetrachloride and cyclohexane at 90°K. Microphotometer tracings are shown in Fig. 1 and the spectral data are listed in Table 6. The light emitted was a strong violet in ethanol, a strong blue in cyclohexane and a weak green-blue in carbon tetrachloride, and the lifetime roughly estimated by visual observation indicated about 2 s in ethanol and cyclohexane and 1 s in carbon tetrachloride. The spectrum of p-dicyanobenzene in ethanol extends from 24,670 to 20,320 cm-l and consists of nine resolved bands. The strong band at 24,670 cm-l is assigned to the O,O-band of the systsm. Frequencies of 820, 1170 and 1590 cm-l are found and
1210
KUNIO TAKEI and YOSHIYA KANDA Table 6.
Phosphorescenoe spectra of p-dicyanobenzene
In ethanol 1F2 mole/l.
In cyclohexane
at 90°K
10m2 mole/l. Analysis
Wave number 24.670
23,850 23,500 23,080 22,685 22,240 21,890 21,510 20,710 20,320
Wave number
Intensity 10
9 9 10
0
820 1170 1590 1985 2430 2780 3160 3980 4350
Intensity
24,560 24,350 24,100 23,730 23,400 22,960 22,740 22,190 21,780
AC 0 210 460 830 1160 1600 1820
7 6
2370 2780
o-o 0 0 0 0 0 0 0 0 0 0 0 0
-
170 470 820 1170 1610 1610 1170 1610 1610 1610 1610 1610
x x x
170 820 820 1170 2 2 - 820 2 - 1170
assigned to Raman frequencies of 820 (a,), 1170 (al) and 1610 (aI) cm-r, respectively. These frequencies appear strong in intensity but the corresponding bands are not found in the infra-red spectrum. This shows that these frequencies are totally symmetric vibrations. Raman spectrum was observed in acetone, methanol and acetic anhydride and the infra-red spectrum was studied by the KBr disk method. These results are shown in Table 8. The phosphorescence spectrum has eleven reasonable bands between 24,810 and 20,800 cm-l in carbon tetrachloride. Vibrational frequencies of 210, 820, 1180 and 1605 cm-l were found, and the last three of these are assigned to totally symmetric (al) vibrations. These data are, however, omitted from Fig. 1 and Table 6. In the cyclohexane spectrum nine bands have been found. The spectrum did not show sharp structure, although the p-isomer is of point group D,, and cyclohexane is a non-polar solvent. A band at 24,560 cm-l is assigned to the O,O-band of the system. The frequencies which appear most strongly are 210, 460, 830, 1160 and 1600 cm-l. The last four are assigned to the al Raman frequencies 470, 820, 1170 and The 1600 cm-l vibration forms the main progression of 1610 cm-l, respectively. the spectrum and the other vibrations appear in combination bands with the 1600 cm-l vibration. The ultraviolet absorption spectrum of the p-isomer was observed in ethanol, in n-hexane and in the vapour. The results are shown in Fig. 3 and in Table 7. The vapour spectrum of p-dicyanobenzene was also observed at 90”-115’C. A strong band at 34,990 cm-l is attributed to the O,O-band of the ultraviolet absorption spectrum. It is noted that several bands were found to the red side of the O,O-band. These bands have been attributed to transitions from several vibrational levels of the ground state to the vibrationless level of the excited one. These are shown in Tables 7 and 8. A band 340 cm-l to the red of the O,O-band has no corresponding frequency in the Raman and infrared data. Frequencies at 835, 1180 and 1580 cm-l to the red side of the 0,0-band correspond to the Raman vibrations of 820, 1170 and
1211
Phosphorescence spectra of benzonitrile and related compounds
33000
35000
37000
Fig. 3. Ultraviolet absorption spectra ofp-dicyanobenzene 1
and in the vapour. 2 . . . in ethanol
. . . in the vapour Table 7. Ultraviolet
0.66
In ethanol x 10e2 mole/l. at 20°C
0.66
in ethanol, in n-hexane 2’
. . . in n-hexane
absorption spectra of p-dicyanobenzene
In n-hexane x 10e3 mole/l. at 20°C
Vapour at 90” N 115°C Analysis
Wave number
E
A;
34,450 34,770 35,200 35,550 35,920 36,330 36,620
87 70 73 85 66 57 54
0 320 .750 1100 1470 1880 2170
37,500
33
3050
Wave number
34,600 34,955 35,400 35,755 36,100 36,520 36,860 37,220 37,580
E
1090 720 870 1000 730 1920 600 465 410
A;
0 355 800 1155 1500 1920 2260 2700 2980
Wave number 33,410 33.770 34,155 34,650 34,990 35,360 35,820 36,170 36,570 36,930 37,300
Intensity m m W W 8 W
m m W W W
Av” -1580 -1180 - 835 - 340 0 370 830 1180 1580 1940 2310
0 0 0 0
-
1580 1180 835 340
030 0,370 0,830 0,118O 0,158O 0,158O + 370 0,158O + 830
1610 cm-l, respectively, all of which are totally symmetric vibrations. The first major band to the ultraviolet side of the O,O-band appears at 35,360 cm-l distant by 370 cm-l. Two strong bands were found at positions separated by 830 and 1180 cm-l from the O,O-band. There is also a strong band at the position separated by 1580 cm-l from the O,O-band. This frequency forms a main progression. It is noteworthy that the frequencies of 830, 1180 and 1580 cm-l in the upper state are very close to those of the ground state. They may also correspond to the Raman frequencies of 820 (a,), 1170 (al) and 1610 (al) cm-l, respectively. The absorption spectrum of p-dicyanobenzene in solution in n-hexane has sharper bands than in ethanol. The O,O-band in ethanol at 34,450 cm-l shifted by 150 cm-l to red compared with that in n-hexane at 34,600 cm-l. This indicates that the
1212
Kumo TAKEI and YOSHIYA KA.NDA Table 8. Ground-state
vibration
Infrared absorption
Raman effect
frequencies in p-dicyanobenzene UV absorption
Phosphorescence
Vapour
In cyclohexane
Symmetry In acetone
In methanol
In acetic anhydride
KBr
disk
210
160 (1)
170 (2)
340 460
a1
835
830
a1
1180
1160
a1
1580
1600
aI
470 (2)
470 (3)
532 562 608 642
w s w m
846 878 973 1026
s w vw v
670 (2) 820 (2)
1175 (4)
1170 (5)
1197 s 1220 (2) 127.5s 1403 m 1508 s 1610 (5)
1610
(1)
1610 (2) 1664 1810 1945 2240 3060 3100
w w w m w w
singlet-singlet absorption system is of n-r * type and the triplet-singlet emission appears through a transition of the same type. A p-dicyanobenzene molecule is treated here as belonging to point group D,,. The electronic transition in ~-dicyanobenzene is considered to be an allowed B3X+-~ls as the transition moment lies along the direction perpendicular to the molecular axis in the molecular plane. The lowest triplet state in benzene is B,,. If the symmetry is reduced from D,, to DZh, .I?,, in D,, goes over to B,, in D,. Therefore, the lowest triplet of p-dicyanobenzene is a B,, level and the triplet-singlet emission has a transition moment along the y axis. The y axis is taken along the molecular axis. The transition sBIU -+ Vls is then allowed by symmetry but forbidden by spin multiplicity. The vibrational analysis of the phosphorescence spectrum conforms with these symmetry properties.
The phosphorescence spectra of o-, m- and p-tolunitriles were studied in ethanol and cyclohexane at 90°K. The results obtanied are shown in Fig. 4 and Tables 9-l 1. The general appearance of the phosphorescence spectra for the three isomers are
1213
Phosphorescence spectra of benzonitrile and related compounds
Fig. 4. Phosphorescence spectra of o-, m- and p-tolunitriles at 90°K. 1 . . . o-isomer in ethanol 1’. . . o-isomer in oyclohexane 2 * m-isomer in ethanol 2?::. ?n-isomer in cyolohexane 3 . . . p-isomer in ethanol 3’ . . . p-isomer in cyclohexane
22000
24000
26000
28000
quite similar each other as shown in Fig. 4, and are analogous to that of dicyanobenzene but quite different from that of xylene [llJ It is assumed that the general appearance of the spectra should be chiefly due to the electronic transition based on resonance between a CN group and a benzene ring. The spectrum of the o-isomer in ethanol extends from 26,550 to 22,265 cm-l. A Table 9. Phosphorescence spectra of o-tol~nit~le at 90°K In ethanol l@ Wave number 26,550 25,820 25,370 24,960 24,250 23,790 23,400 22,700 22,265
mole/l.
Intensity 9 6 8 9 8 7 7 6 5
AY 0 730 1180 1590 2300 2760 3150 3850 4285
In cyclohsxane Wave number 26,450 25,730 25,265 24,860 24,150 23,710 23,280 22 )550
1(F3 mole/l. Analysis
Intensity 7 3 6 8 7 6 5 4
A; 0 720 1185 1590 2300 2740 3170 3900
090 0 0 0 0 0 0 0 0 -
715 1159 1599 1599 1599 1599 1599 1599
x x x
715 1159 2 2 - 715 2 - 1159
strong band at 26,550 cm-r is ascribed to the O,O-band of the system. Vibrational frequencies of 730, 1180 and 1590 cm-l were found. The 1590 cm-1 frequency constituted a main progression and the other frequencies were seen to appear as combination bands with the frequency. The frequencies 730, 1180 and 1590 cm-l [II]
L. A. BRACKWELL,Y. KANDA, and H. SPONER,J. Chews,.Phys. 32, 1465 (1960).
1214
KUNIO TAKEI and YOSRIYA KANDA Table In ethanol
Wave number
lo-3 mole/l.
Intensity
26,340 25,650 25,190 24,750 24,070 23,600 23,170 22,520 22,050
8 4 6 7 6 6 6 5 4
Table In ethanol Wave number 26,500 26,070 25,700 26,320 24,900 24,485 24,110 23,760 23,300 22,900 22,530 22,140 21,720 21,360
10. Phosphorescence
-
AC 0 690 1150 1590 2270 2740 3170 3820 4290
Intensity 10 4 7 8 9 7 8 8 8 7 7 6 5 5
AY” 0 430 800 1180 1600 2015 2390 2740 3200 3600 3970 4360 4780 5140
of m-tolunitrile
In cyclohexane Wave number
10m3mole/l.
Intensity 6 2 4 5 4 4 4 3
spectra
In cyclohexane Wave number
at 90°K
Analysis
26,270 25,580 25,120 24,680 24,030 23,520 23,110 22,420
11. Phosphorescence
1e3 mole/ 1.
spectra
As 0 690 1150 1590 2240 2750 3160 3850
of p-tolunitrile
090
0 0 0 0 0 0 0 0
-
707 1149 1597 1597 1597 1597 1597 1597
x x x
707 1149 2 2 - 707 2 - 1149
at 90°K
1e3 mole/l. Analysis
Intensity
Ay”
26,410
4
0
25,630 25,230 24,810
2 4 6
780 1180 1600
24,050 23,645 23,200
5 4 4
2360 2765 3210
070 0 0 0 0 0 0 0 0 0 0 6 0 0 -
410 819 1194 1604 1604 1604 1604 1604 1604 1604 1604 1604 1604
x x x x x x
410 819 1194 2 2 - 410 2 - 819 2 - 1194 3 3 - 410
correspond to Raman lines 715, 1159 and 1599 cm-l, respectively. They are all assigned to totally symmetric vibrations. The analysis of the spectrum is listed in the last column in Table 9. The analyses of the other isomers in ethanol and in cyclohexane are treated in a similar way. The infrared absorption spectra have also been studied and the results are listed in Table 12, where the ground state frequencies obtained by Raman effect [12], infrared and phosphorescence spectra of tolunitriles are compared. [12] [13] [14] [15]
LANDOLT-B~RNSTAIN, Phys. Chem. Tabell. Dritter ErgLnz.Band 2, 1154 (1935). R. MECKE, Docurnent. MolecuE. Spectra. 3381 Butterworths, London (1958). K. IUSA~I, Bull. Chem. Sot. Japan 11,346 (1936). 9. BARCHEWITZ and M. PARODI, J. phys. radiunz 10,143 (1939).
1215
Phosphorescence spectra of benzonitrile and related compounds Table 12.
Ground-state
meta
para
159 (7)
161 (7)
220 (5) 338 (0) 385 (0.5)
252 (3) 345 (1)
159 167 219 342 385
(4) (8) (4) (1) (1)
457 541 559 590
(8) (6) (1) (3)
459 (3) 522 (4) 576 (1)
410 437 516 549
715 (9) 761 (2)
707 (4)
648 (4) 705 (1)
790 (0) 819 (3)
ortho
meta
para
707 755 795 817 840 865
702 w
704 m 755 w
797 (2) 819 (8)
8 s w w w w
907 w 943 m 980 w
995 (8)
1045 (8)
1042 m
1108 (2)
1109m 1149 (1) 1169 (4)
1172 (10)
w m w m
1036 m 1060 w 1073 w 1094m 1145 w 1165 w
1211 m
1384 m
1225 1236 1281 1315 1380
1460 w 1485 s
1460 w 1487 s
1577 w 1602 m 1625 w
1580 w 1602 m
1288 m 1309 (0) 1378 (2) 1445 (0)
1486 (3) 1571 (3) 1599 (9)
1583 (3) 1597 (4)
1604 (10)
1812 w 1845 w 1890 w
a1
780
a1
908 w 948 w
w w m w m
1019 w 1037 w
1102 w 1120 m 1175m 1195 1210 1272 1288 1308 1383 1412 1450
1510 m 1575 w 1607m
1755 w 1789 w 1810 w 1855 w 1885 w
1185
1150
1180
a1
1590
1590
1600
a1
w w w w w w w w
1695 w 1705 w 1735 w
8
690
para
996 m
1160 m
1245 (4) 1287 (1) 1376 (1)
720
815 s 850 878 896 910
1194 (4) 1209 (10)
1378 (4)
mete
783 s
1020 (0)
1159 (5)
ortho
Symmetry
(4) (1) (0) (3)
896 (1)
991 (1)
Phosphorescence in cyclohexane
Infrared absorption
Raman effect * ortho
vibration frequencies in tolunitriles
KUNIO TAKEI and YOSHIYA KANDA
1216
Table 12
Infra-red absorption
Raman effect * ortho
meta
(Contd)
para
ortho
meta
1927 w
para
Phosphorescence in cyclohexane ortho
meta
Symmetry
para
1920 w 1946 w
2225 (12)
2232 (10)
2228 (10)
2876 (1) 2922 (1)
2877 (0) 2928 (1)
3050 (3) 3070 (2)
3053 (3)
2875 2926 3007 3043
(2) (1) (0) (4)
1965 2150 2225 2300 2850 2910 3018 3050
w s s w w w w w
2230 s
2230 s
2908 w 3020 w
2900 w 3020 w
* See reference [12]. Acknowledgement-The authors wish to express their sincere thanks to Dr. R. SHIMADA in this laboratory for his helpful discussion on this work. Special thanks are also due to Fuji PhotoFilm Company for the generous offer of highly sensitive plates. They are indebted to the Ministry of Education for a grant-in-aid out of the Scientific Research Expenditure.
1962,
Vol. 18,
pp.1201to 1216.Pergamon Press Ltd.Printed inNorthern Ireland
Phosphorescence spectra of benzonitrile and related compounds KUNIO TAKEI* and YOSHIYA KANDA Department of Chemistry, Faculty of Science, Kyushu University, Fukuoke, Japan (Received
2 Februaq
1962)
Abstract-The phosphorescence spectra of benzonitrile, o- and p-dioyanobenzenes and o-, mand p-tohmitriles have been studied in ethanol and in cyclohexane at liquid sir temperature. Benzonitrile in ethanol gives a sharp spectrum beginning at 26,910 cm-l, and an even sharper one in cyclohexane beginning at 26,780 cm- l. Conversely, the spectra of o- and p-dicyanobenxenes in ethanol are sharper than those in cyclohexane. The 0,0-band of the spectrum of the o-isomer has been found at 25,440 cm-l in ethanol and 25,340 cm-l in cyclohexrtne, and that of the p-isomer at 24,670 cm-r in ethanol and 24,560 cm-l in cyclohexane. The general appearance of the spectra, of o-, m- and p-tolunitriles is quite similar to one another, and the structure resembles that of the dicyanobenzene spectra. Vibrational analyses of these spectra are discussed. INTRODUCTION KOWALSKI
[l]
found ten phosphorescence
bands of benzonitrile
between
371 m,u
(26,950 cm-l) and 451 rnp (22,170 cm-l) in 1912. LEWIS and KASHA [2] reported the triplet-singlet emission of benzonitrile in EPA at 90°K and assigned a strong band at 27,000 cm-l to the O,O-band of the system. HIRT and HOWE [3] investigated the ultraviolet absorption spectrum of benzonitrile. BASS [4] studied the fluorescence spectrum of benzonitrile vapour. They performed successful analyses of the spectra and concluded that the electronic transition of benzonitrile is Al---B, in analogy to the SPONER and WOLLMAN [5] treatment of monochlorobenzene. Benzonitrile has been investigated in the Rnman effect [6] and in infra-red absorption [7]. Recently GREEN [8] studied the Raman shifts of benzonitrile and assigned the vibrational spectra. On the other hand, no data has been reported on the triplet-singlet emission of o- and p-dicyanobenzenes and o-, m- and p-tolunitriles. We studied the triplet-singlet spectra of benzonitrile, o- and p-isomers of dicyanobenzenes, and o-, m- and p-isomers of tolunitrile. Raman, infra-red, and ultraviolet spectra of those compounds were also studied. Their vibrational analyses will be discussed. * Present address: Department of Engineering Chemistry, Faculty of Engineering, Miyazaki University, Miyazaki, Japan. [l] [2] [3] [4] [5] [6]
J. VON Kowtisxr, Physik. 2. 12, 956 (1912). G. N. LEWIS and M. KAS~, J. Am. Chem. Sot. 66, 2100 (1943). R. C. HIRT and J. P. HOWE, J. Chem. Phys. 16, 480 (1948). A. M. BASS, J. Chem. Phys. 18, 1403 (1950). H. SPONER and S. WOLLMAN, J. Chem. Phy8. 9,816 (1941). L. SIMONS,Sot.Sci.Fennica, Comment&ones Phy. Math. 6,13 (1932). K. W. F. KOHLRAUSCH end A. PONGRATZ, Sitzber. Akad. Wiss. Wien 142,637 (1933); Monatsh. Chem. 63,427 (1937). [7] J. LECOMTE, J. Phys. radium 8, 489 (1937). [S] J. H. S. GREEN, Spectrochim. Acta 17, 607 (1961). 1201
KUNIOTAKEIand YOSHIYAKANDA
1202
EXPERIMENTAL Benzonitrile and o-dicyanobenzene were obtained from Tokyo Kasei Co. Benzonitrile was washed with a sodium carbonate solution in order to remove benzoic acid. It was then dissolved in ether, washed with water and dried with calcium chloride. The solution was filtered and ether was removed by distillation. The residue was fractionally distilled twice under reduced pressure. o-Dicyanobenzene was sublimed twice under reduced pressure, recrystallized from acetone and dried at 100°C for 1 hr. The melting point was 161*5”C. p-Dicyanobenzene was obtained from Dozin Chemical Institute, Kumamoto, Japan. The melting point was 222°C. It was warmed under reduced pressure in order to remove a trace of benzene. Three isomers of tolunitriles were obtained from Tokyo Kasei Co. They were carefully distilled under reduced pressure. Ethanol and cyclohexane were purified in the same way as that reported previously [9]. The purified benzonitrile, o- and p-dicyanobenzenes and tolunitriles were dissolved in ethanol and in cyclohexane at the concentration of 1O-2 or 10es mole/l. The phosphorescence cell, the phosphoroscope and other apparatus used in this work were the same as those reported previously [9]. RESULTS AND DISCUSSION (a) Benxonitrile The phosphorescence spectrum of benzonitrile was observed in ethanol and cyclohexane at 90°K. Microphotometer tracings are shown in Fig. 1 and the spectral data are given in Table 1. The general appearance of the spectra of benzonitrile resembles Table In ethanol
1. Phosphorescence In cyclohexane ___
1w3 mole/l.
__~ Wave number
Intensity
AG
26,910 26,460 26,150
9 4 6
0 450 760
25,740 25,310 24,990
8 9 8
1170 1600 1920
24,590
8
2320
24,150 23,710 23,400
9 8 7
2760 3200 3510
22,990
8
3920
22 560 221110 21,450
7 6 4
4350 4800 5460
[Q] Y. KANDA
spectra
Wave number 26,780 26,315 26,010 25,790 25,600 25,175 24,820 24,590 24,410 24,180 24,000 23,580 23,230 22,970 22,800 22,570 22,400 21,940 21,380 20,830
of benzonitrile
at 90°K
low3 mole/l.
Intensity 9 5 7 8 9 9 8 8 8 9 9 8 8 7 7 7 7 6 5 5
and R. SHIMADA, Spectrochim. Acta
Av” 0 465 770 990 1180 1605 1960 2190 2370 2600 2780 3200 3550 3810 3980 4210 4380 4840 5400 5950
Analysis o-o 0 - 460 0 - 765 0 - 998 0 - 1178 0 - 1597 0 - 1178 0 - 1178 0 - 1178 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597 0 - 1597
15, 211 (1959);
x x x x x x x
765 998 2 998 1178 2 1178 1178 1178 2 2 3 2 3 -
17, 1 (1961).
- 765 - 998 x 2 998 1178 1178 1178
998
Phosphorescence spectra of benzonitrile and related compounds
20000 Fig. 1. Phosphorescence 1 1’ 2 2’ 3 3’
22000
24000
26000
1203
26000
spectra of benzonitrile and related compounds at 90°K.
. . . benzonitrile in ethanol . . . benzonitrile in cyclohexane . . . o-dicyanobenzene in ethanol . . . o-dicyanobenzene in cyclohexane . . . p-dicyanobenzene in ethanol . . . p-dicyanobenzene in cyclohexane
those of o- and p-dicyanobenzenes. The spectrum of benzonitrile in cyclohexane gave a very fine structure. The lifetime of the phosphorescence in ethanol was visually estimated to be about 3 set and that in cyclohexane about 2. The phosphorescence in ethanol was a strong violet, and the exposure time was 2 hr with a slit width of 100 ,Uand Eastman Kodak Tri-X film. The phosphorescence in cyclohexane was weak violet and the exposure time ranged from 7 to 10 hr. Fourteen bands were found in the ethanol spectrum. KOWALSKI [I] found ten bands between 26,950 and 22,170 cm-l. LEWIS and KASHA [2] found the O,O-band at 27,000 cm-l. We found that the O,O-band lay at 26,910 cm-l. HIRT and HOWE [3] found the O,O-band at 36,516 cm-l in the ultraviolet absorption spectrum of benzonitrile. The S’-T difference in frequency is 9606 cm-l. This value seems reasonable for the S-T separation of n--r * type. A very weak band was found at 26,460 cm-l separated by 450 cm-l from the O,O-band to the longer wavelengths. The difference frequency may be assigned to the Raman vibration of 460 cm-l. This vibration is a moderately strong band in the Raman spectrum but does not appear in infra-red spectrum. It may be assumed to be a totally symmetric vibration. The next prominent band is a band of medium intensity with a frequency of 760 cm-l. The frequency appears in multiples and combinations with the 1600 cm-l progression and indicates that it is a totally symmetric vibration. In the fluorescence spectrum of benzonitrile BASS [4] found a frequency of 771 cm-1 and assumed it to correspond to
1204
KUNIO TAKEIand
YOSHIYA
KANDA
Table 2. Ground-state vibration frequenciesin benzonitrile Ramcln effect
KOHLRAUSCH
HIRT and HOWE
WI
131
170 ((lb, O&T)
170 (10)
381 (2, 0.36)
378 (3)
460 (6) 549 (6) 024 (5, 0.84)
460 (6) 548 (5) 623 (5)
Tnfra-red absorption
GREEN
181
LECOMTE
PI
172 (m) dp 320 (VW) 381 (w) dp 405 (TV) 460 (8) P 549 (8) dp 624 (m) dp 650 (w)
0.15
762 (4) 764 (6)
751 (m) P 765 (m) P
K48 616
922
1001 (10) 1026 (3)
997 (4 P 1023 (m) p
1178 (8, 0.24)
1178
1178 (s) dp
1190 (8)
1102
1190 (8) p
462t 548t 624 (w) 660 (VW) 675 (ah) 687 (s) 701 (ah)
1002
1310 (w)
1353 (0)
1353 (w)
1447 (1)
1445 (w) dp
1391 (In) 1443 (s)
1493 (2)
1498 (m)
1486 (8)
1598 (10)
1600 (8) dp
1131
542 (8)
MASAKI
WI
469 547 616
HLRT and HOWE
r3i
Fluorescenoe -~
BASS
M
170 269 314 380
173 270 314 382
462 548 626
462 548 618
Phosphoresce*ce
This research
465
670 687 (10)
768 (8) 756 (10) 798 (ah) 844 (w) 888 (ah) 889 (ah) 926 (8) 921 (4) 068 (VW) 987 (VW) 1001 (m) 1020 (4) 1026 (8) 1028 (4) 1032 (4) 1060 (3) 1071 (5) 1072 (3) 1098 (m) 1163 (8) 1151 (0) 1171 (1) 1176 (8) 1176 (1) 1183 (1) 1192 (s) 1216 (sh) 1275 (2) 1287 (8) 1282 (2) 1312 (w) 1323 (0) 1333 (m) 1335 (0)
1310 (1)
1597 (IO, 0+38)
MIWXE
681
754
838
998 (15, 0.04) 1023 (3)
iSI
208* 263* 313* 383*
616 686 761 (3) 765 (5)
GREEN
UV absorption
1440 (5) 1461 (5) 1486 (7) 1492 (7) 1497 (7)
1520 (VW) 1670 (ah) 1577 (In) 1595 (8) 1585 (3) 1681 (w) 1667 (1) 1715 (w) 1745 (1) 1761 (w) 1812 (w) 1795 (2) 1894 (w) 1890 (2)
1009
141 773
(751) 771
841
845
1003 1026
1176
770
990
1180
1194
1311 (1349)
1498
1603
1605
1205
Phosphorescence spectra of benzonitrile and related compounds Table 2. (Co&d) Infra-red absorption
Ramm effect
WV absorption
KOELRAU~C~
HIRT and HOWE
GREEN
LECOMTE
GREEN
MECKE
[‘A
[31
PI
[71
PI
[I31
2224 (lob, 0.23) 3071 (Sb, 0.30) 3146 (1) 3196 (1)
2229 (10) 3071 (8)
2222 (8) p
1961 (w) 2222 (8) 3039 (8)
MASAKI
v41
Flumes- Phosphorcence escenoe ______
HIECT and HOWE
BASS
[31
[41
1967 (2) 2222 (5) 3039 (7)
This research
(2228)
3071 (8) p
* Values from BARCHEWITZ and PARODI [15]. t Values from MECKE [13].
C-CN bond vibration. It is, therefore, assumed that the frequency 760 cm-1 The next prominent band, the third corresponds to the C-CN bond vibration. strongest in the spectrum, is at 1170 cm-i from the O,O-band and may be assigned to the Raman vibration of 1178 cm- l. This is the strongest line in the Raman spectrum and has a depolarization factor of 0.24. It may also be a totally symmetric vibration. This frequency 1170 cm-l also occurs in overtones up to the third and in combination with a progression of 1600 cm-l. The vibrational frequency of 1600 cm-l of benzonitrile concerns the second strongest band in ethanol and assigned to the totally symmetrical Raman line of strong intensity at 1597 cm-l. This frequency forms a main progression of the spectrum in ethanol. Twenty bands were found in the spectrum in cyclohexane. The O,O-band lies at 26,780 cm-i which is shifted about 130 cm-l toward the red from the corresponding band in ethanol. The vibrations which appear strongly in the phosphorescence spectrum have the frequencies of 465, 770, 990, 1180 and 1605 cm-l. The spectral data are listed in Table 1. The analysis of the cyclohexane spectrum is shown at the last column in Table 1. The frequencies of 465, 770, 1180 and 1605 cm-l may be of totally symmetric vibrations by the same treatment as that of the spectrum in ethanol. The 990 cm-l frequency is assigned to the Raman frequency of 998 cm-l, which is the strongest line and corresponds to a ring vibration of 992 cm-l in benzene. It is noteworthy that the observed vibrational frequencies in cyclohexane are generally larger than the corresponding ones in ethanol. The fundamental ground state frequencies which were observed in the phosphorescence spectrum in cyclohexane are collected in Table 2 and compared with the value obtained through other methods by other workers. It might be assumed that the phosphorescence spectrum of benzonitrile is somewhat similar to that of toluene studied by KANDA and SPONER [lo]. However, the intensity of the O,O-band of the benzonitrile spectrum is relatively stronger than that of the toluene spectrum. This suggests that a CSN group resonates with a benzene nucleus and this resonance gives rise to stabilization also in the upper state. A similar phenomenon was found in the phosphorescence spectrum of biphenyl [ 101.
a,
[lo]
KANDA and H. SPONER, J. Chem. Phys. Y. SAKAI, Spectrochim. Acta 17, 1 (1961).
Y.
28, 798 (1958);
Y.
KANDA,
R.
SHINADA
and
1206
KUNIO TAKEI and YOSHIYA KANDA
Hnt~ and HOWE reported that the electronic transition of benzonitrile is lBp--lA,, its moment lying in the plane of the ring and perpendicular to the molecular axis. We assumed the molecular structure of benzonitrile at 90°K has also the same point group C,,. Therefore, the phospohrescence process must be of 3A, -+ lA,. (b) o-Dicyanobenzene The phospohrescence spectrum of o-dicyanobenzene was observed in ethanol and cyclohexane at 90°K. Microphotometer tracings are presented in Fig. 1 and the spectral data are listed in Table 3. The light emitted is a strong violet and the exposure time ranged from 2 h in ethanol to 10 hr in cyclohexane with a slit width of 100 ,u and Fuji special test plates. The lifetime was roughly estimated by visual observation to be about 2 s in ethanol and 1 s in cyclohexane. Ten bands were found between 25,440 and 21,710 cm-l in ethanol spectrum. A strong band lies at 25,440 cm-l and is assigned to the O,O-band of the spectrum. It Table 3. Phosphorescence spectra of o-dicyanobenzene In cyclohexane
In ethanol 10m3mole/l. Wave number
25,440 24,760 24,295 23,905 23,620 23,220 22,750 22,380 22,070 21,710
Intensity
8
AF 0
680 1145 1535 1820 2220 2690 3060 3370 3730
Wave number
at 90°K
10e2 mole/l. Analysis
Intensity
Ai;
25,340 25,190 24,640 24,180 23,775
7 7 9 10
150 700 1160 1565
23,070 22,630 22,240 21,920 21,530 21,090
9 9 8 8 7 5
2270 2710 3100 3420 3810 4250
9
0
o-o
0 0 0 0 0 0 0 0 0 0 0
-
172 705 1175 1590 1175 1590 1590 1590 1590 1590 1590
x x x
705 705 1175 2 1175 - 705 2 - 705 2 - 1175
lies at 1470 cm-l toward longer wavelengths from the O,O-band of benzonitrile in ethanol. A separation of 680 cm-l from O,O-band is barely found and is assigned to the Raman line at 705 cm-l (ai). A separation of 1145 cm-l is assigned to the Raman frequency of 1175 cm-l (ai). Both frequencies of 680 and 1145 cm-l appear in combination with the 0,0-band and with the 1535 cm-l progression throughout the spectrum. The 1535 cm-l frequency is assigned to a totally symmetric Raman frequency 1590 cm-r. We studied the Raman and infrared spectra of this compound and the results are The Raman spectrum given in the first and second columns in Table 5, respectively. was observed in an acetone solution and the infra-red spectrum was measured by the KBr disk method. The Eleven bands were found in the phosphorescence spectrum in cyclohexane. tracing curves are shown in Fig. 1 and the spectral analysis is listed in the last column in Table 3. The light emitted was weaker than that in ethanol. A band at 25,340 cm-l are ascribed to the O,O-band. A shoulder was found on the red side of the O,Oband and the separation was estimated to be 150 cm-l. We found Raman lines at
Phosphorescence
spectra
of benzonitrile
and related
1207
compounds
140 and 172 cm-l in the Raman spectrum of o-dicyanobenzene but it is uncertain whether the frequency of 150 cm-l in the phosphorescence spectrum should be assigned to the Raman line at 140cm-l or at 172cm- l. Other vibrational frequencies found in the phosphorescence spectrum in cyclohexane were 700, 1160 and 1565cm-l and they were assigned to Raman frequencies of 705, 1175 and 1590 cm-l, respectively. The frequency of 1590 cm-l was seen to form a main progression. The ultraviolet absorption spectrum of this compound was observed in ethanol, in n-hexane and in the vapour and the results are shown in Fig. 2 and Table 4. The
34000
Fig. 2. Ultraviolet 1
absorption
. . . in the vapour Table
In ethanol lop4 mole/l at 20°C
4. Ultraviolet
36000
36000
spectra of o-dicyanobenzene in ethanol, in n-hexane and in the vapour. 2’. . . in n-hexane 2 . . . in ethanol absorption
spectra
of o-dicyanobenzene.
Vapour at 70” N 90°C
In n-hexane lop3 mole/l at 20°C
Analysis Wave number
34,425
35,140
E
8600
7200
Wave number
A;
0
715
34,530
35,180
E
570
420
Wave number
A;
0
650
35,580
7900 1155
35,670
470
1140
36,325
6400 1900
36,380
360
1850
37,230
4900 2805
37,300
250
2770
34,780 34,820 34,855 34,895 35,450 35,490 35,525 35,570 35,740 35,780 35,820 35,865 36,010 36,050 36,090 36,520 36,750 37,095 37,275 37,700 37.956
Intensity w w
m m VW W W
m w W W
m w W
m W W W W W W
-~~ -115 -75 -40 0 555 595 630 675 845 895 925 970 1115 1155 1195 1625 1855 2200 2380 2805 3055
0-40x3 0-40x2 0 - 40 030 0,675 - 40 x 3 0,675 - 40 x 2 0,675 - 40 0,675 0,970 - 40 x 3 0,970 - 40 x 2 0,970 - 40 0,970 0,1195 - 40 x 2 0,1195 - 40 0,1195 0,675 + 970 0,675 + 1195 0,970 + 1195 0,1195 x 2 0,675 + 970 + 1195 0,675 + 1195 x 2
KUNIO TAKEI and YOSHIYAKANDA
1208
Table ci. ~ro~d-s~te Rwnan effect in acetone -._140 (4) 172 (2) 563 {Z) 612 (1) 663 (1) 705 (2)
984 (2) 1032 (4)
117.5(I) 1205 (6)
1296 (2)
1590 (3b)
2230 (Sb)
Infra-red absorption KBr disk
vibration frequencies in c-dicyanobenzene UT absorption Phosphorescence in cyclohexane in vapour ~--~ 150
666 VW b 702 m 768 vs 803 m 850 VW b 882 VW 904 w 922 w 939 YW 961 s 1030 VW 1052 VW 1078 VW b 1087 vw 1145 vw 1178 w 1186 VW 3202 8 1222 s 1245 w 1293 s 1347 VW 1400 w b 1447 s 1487 vs 1572 m 1590 s 1657 w b 1737 w b 1768 w 1847 w b 1885 w 1930 w 1968 w 1998 w 2232 vs 2338 w 2590 w 2630 w 2750 T 3032 m 3068 m 3090 111
678
700
970
Ilt95
1160
1565
symmetry
Phosphorescence spectra of benzonitrile and related compounds
1209
most prominent feature of the ultraviolet absorption spectrum of o-dicyanobenzene vapour is the group of bands culminating at a band at 34,895 cm-l in intensity with an extremely sharp edge on the ultraviolet side. This band is taken at the O,O-band. The general appearance of the spectrum is very similar to that of benzonitrile. Several bands on the red side of the O,O-band are attributed to difference due to socalled w-v transitions. The spacing of 40 cm-l and its multiples appear quite often in the ultraviolet spectrum. The same difference was also found in the absorption spectrum of benzonitrile vapour. The first major band appeared at 35,570 cm-l, distant by 675 cm-P to the ultraviolet side of the O,O-band. This frequency is assigned to a vibrational frequency of the upper state and corresponds to a Raman frequency of 705 cm-l (al). On the red side of this band several bands of spacing 40 cm-l were also found. Two strong bands were found at positions separated by 970 and 1195 cm-l from the O,O-band and accompanied by weaker bands to their red sides. The frequency of 970 cm-l is assigned to 1032 cm-l Raman vibration, which is attributed to the symmetric ring The frequency of 1195 cm-l is assigned to 1175 cm-l (al) breathing vibration. Raman vibration. Six bands are found on the ultraviolet side of the band at 36,090 cm-l (O-1195 cm-l). The spectral analyses of these bands are shown in Table 4. The absorption spectrum of o-dicyanobenzene in solution in ethanol is similar to that in n-hexane as shown in Fig. 2. The strong band at 34,425 cm-l in ethanol is assigned to the O,O-band of the system. The O,O-band in n-hexane, however, was observed at 34,530 cm-l. The spectrum in ethanol shows a red shift compared with that in n-hexane. Therefore, the singlet-singlet absorption system is of W-T* type and the same is deduced for the triplet-singlet emission. By analogy to the SPONER [5] treatment of o-dichlorobenzene, the electronic transition for o-dicyanobenzene is IA, +- IA,. The ground state vibrational frequencies of the o-isomer are listed in Table 5, where symmetry assignments are included. The lowest triplet state in benzene is B,,. If the symmetry is reduced from D,, to CZV,to which o-dicyanobenzene belongs, B,, in D,, goes over to B,. Therefore, the lowest triplet of o-dicyanobenzene in a B, level and the triplet-singlet emission has a transition moment along the y axis. The y axis is taken along the perpendicular direction to the molecular axis in the plane. The transition 3B, -+ l.4, is then allowed by symmetry but forbidden by spin multiplicity. The vibrational analyses of the phosphorescence spectra conform with these symmetry properties. (c) p-Die yanobenzene The phosphorescence spectrum of p-dicyanobenzene was studied in ethanol, carbon tetrachloride and cyclohexane at 90°K. Microphotometer tracings are shown in Fig. 1 and the spectral data are listed in Table 6. The light emitted was a strong violet in ethanol, a strong blue in cyclohexane and a weak green-blue in carbon tetrachloride, and the lifetime roughly estimated by visual observation indicated about 2 s in ethanol and cyclohexane and 1 s in carbon tetrachloride. The spectrum of p-dicyanobenzene in ethanol extends from 24,670 to 20,320 cm-l and consists of nine resolved bands. The strong band at 24,670 cm-l is assigned to the O,O-band of the systsm. Frequencies of 820, 1170 and 1590 cm-l are found and
1210
KUNIO TAKEI and YOSHIYA KANDA Table 6.
Phosphorescenoe spectra of p-dicyanobenzene
In ethanol 1F2 mole/l.
In cyclohexane
at 90°K
10m2 mole/l. Analysis
Wave number 24.670
23,850 23,500 23,080 22,685 22,240 21,890 21,510 20,710 20,320
Wave number
Intensity 10
9 9 10
0
820 1170 1590 1985 2430 2780 3160 3980 4350
Intensity
24,560 24,350 24,100 23,730 23,400 22,960 22,740 22,190 21,780
AC 0 210 460 830 1160 1600 1820
7 6
2370 2780
o-o 0 0 0 0 0 0 0 0 0 0 0 0
-
170 470 820 1170 1610 1610 1170 1610 1610 1610 1610 1610
x x x
170 820 820 1170 2 2 - 820 2 - 1170
assigned to Raman frequencies of 820 (a,), 1170 (al) and 1610 (aI) cm-r, respectively. These frequencies appear strong in intensity but the corresponding bands are not found in the infra-red spectrum. This shows that these frequencies are totally symmetric vibrations. Raman spectrum was observed in acetone, methanol and acetic anhydride and the infra-red spectrum was studied by the KBr disk method. These results are shown in Table 8. The phosphorescence spectrum has eleven reasonable bands between 24,810 and 20,800 cm-l in carbon tetrachloride. Vibrational frequencies of 210, 820, 1180 and 1605 cm-l were found, and the last three of these are assigned to totally symmetric (al) vibrations. These data are, however, omitted from Fig. 1 and Table 6. In the cyclohexane spectrum nine bands have been found. The spectrum did not show sharp structure, although the p-isomer is of point group D,, and cyclohexane is a non-polar solvent. A band at 24,560 cm-l is assigned to the O,O-band of the system. The frequencies which appear most strongly are 210, 460, 830, 1160 and 1600 cm-l. The last four are assigned to the al Raman frequencies 470, 820, 1170 and The 1600 cm-l vibration forms the main progression of 1610 cm-l, respectively. the spectrum and the other vibrations appear in combination bands with the 1600 cm-l vibration. The ultraviolet absorption spectrum of the p-isomer was observed in ethanol, in n-hexane and in the vapour. The results are shown in Fig. 3 and in Table 7. The vapour spectrum of p-dicyanobenzene was also observed at 90”-115’C. A strong band at 34,990 cm-l is attributed to the O,O-band of the ultraviolet absorption spectrum. It is noted that several bands were found to the red side of the O,O-band. These bands have been attributed to transitions from several vibrational levels of the ground state to the vibrationless level of the excited one. These are shown in Tables 7 and 8. A band 340 cm-l to the red of the O,O-band has no corresponding frequency in the Raman and infrared data. Frequencies at 835, 1180 and 1580 cm-l to the red side of the 0,0-band correspond to the Raman vibrations of 820, 1170 and
1211
Phosphorescence spectra of benzonitrile and related compounds
33000
35000
37000
Fig. 3. Ultraviolet absorption spectra ofp-dicyanobenzene 1
and in the vapour. 2 . . . in ethanol
. . . in the vapour Table 7. Ultraviolet
0.66
In ethanol x 10e2 mole/l. at 20°C
0.66
in ethanol, in n-hexane 2’
. . . in n-hexane
absorption spectra of p-dicyanobenzene
In n-hexane x 10e3 mole/l. at 20°C
Vapour at 90” N 115°C Analysis
Wave number
E
A;
34,450 34,770 35,200 35,550 35,920 36,330 36,620
87 70 73 85 66 57 54
0 320 .750 1100 1470 1880 2170
37,500
33
3050
Wave number
34,600 34,955 35,400 35,755 36,100 36,520 36,860 37,220 37,580
E
1090 720 870 1000 730 1920 600 465 410
A;
0 355 800 1155 1500 1920 2260 2700 2980
Wave number 33,410 33.770 34,155 34,650 34,990 35,360 35,820 36,170 36,570 36,930 37,300
Intensity m m W W 8 W
m m W W W
Av” -1580 -1180 - 835 - 340 0 370 830 1180 1580 1940 2310
0 0 0 0
-
1580 1180 835 340
030 0,370 0,830 0,118O 0,158O 0,158O + 370 0,158O + 830
1610 cm-l, respectively, all of which are totally symmetric vibrations. The first major band to the ultraviolet side of the O,O-band appears at 35,360 cm-l distant by 370 cm-l. Two strong bands were found at positions separated by 830 and 1180 cm-l from the O,O-band. There is also a strong band at the position separated by 1580 cm-l from the O,O-band. This frequency forms a main progression. It is noteworthy that the frequencies of 830, 1180 and 1580 cm-l in the upper state are very close to those of the ground state. They may also correspond to the Raman frequencies of 820 (a,), 1170 (al) and 1610 (al) cm-l, respectively. The absorption spectrum of p-dicyanobenzene in solution in n-hexane has sharper bands than in ethanol. The O,O-band in ethanol at 34,450 cm-l shifted by 150 cm-l to red compared with that in n-hexane at 34,600 cm-l. This indicates that the
1212
Kumo TAKEI and YOSHIYA KA.NDA Table 8. Ground-state
vibration
Infrared absorption
Raman effect
frequencies in p-dicyanobenzene UV absorption
Phosphorescence
Vapour
In cyclohexane
Symmetry In acetone
In methanol
In acetic anhydride
KBr
disk
210
160 (1)
170 (2)
340 460
a1
835
830
a1
1180
1160
a1
1580
1600
aI
470 (2)
470 (3)
532 562 608 642
w s w m
846 878 973 1026
s w vw v
670 (2) 820 (2)
1175 (4)
1170 (5)
1197 s 1220 (2) 127.5s 1403 m 1508 s 1610 (5)
1610
(1)
1610 (2) 1664 1810 1945 2240 3060 3100
w w w m w w
singlet-singlet absorption system is of n-r * type and the triplet-singlet emission appears through a transition of the same type. A p-dicyanobenzene molecule is treated here as belonging to point group D,,. The electronic transition in ~-dicyanobenzene is considered to be an allowed B3X+-~ls as the transition moment lies along the direction perpendicular to the molecular axis in the molecular plane. The lowest triplet state in benzene is B,,. If the symmetry is reduced from D,, to DZh, .I?,, in D,, goes over to B,, in D,. Therefore, the lowest triplet of p-dicyanobenzene is a B,, level and the triplet-singlet emission has a transition moment along the y axis. The y axis is taken along the molecular axis. The transition sBIU -+ Vls is then allowed by symmetry but forbidden by spin multiplicity. The vibrational analysis of the phosphorescence spectrum conforms with these symmetry properties.
The phosphorescence spectra of o-, m- and p-tolunitriles were studied in ethanol and cyclohexane at 90°K. The results obtanied are shown in Fig. 4 and Tables 9-l 1. The general appearance of the phosphorescence spectra for the three isomers are
1213
Phosphorescence spectra of benzonitrile and related compounds
Fig. 4. Phosphorescence spectra of o-, m- and p-tolunitriles at 90°K. 1 . . . o-isomer in ethanol 1’. . . o-isomer in oyclohexane 2 * m-isomer in ethanol 2?::. ?n-isomer in cyolohexane 3 . . . p-isomer in ethanol 3’ . . . p-isomer in cyclohexane
22000
24000
26000
28000
quite similar each other as shown in Fig. 4, and are analogous to that of dicyanobenzene but quite different from that of xylene [llJ It is assumed that the general appearance of the spectra should be chiefly due to the electronic transition based on resonance between a CN group and a benzene ring. The spectrum of the o-isomer in ethanol extends from 26,550 to 22,265 cm-l. A Table 9. Phosphorescence spectra of o-tol~nit~le at 90°K In ethanol l@ Wave number 26,550 25,820 25,370 24,960 24,250 23,790 23,400 22,700 22,265
mole/l.
Intensity 9 6 8 9 8 7 7 6 5
AY 0 730 1180 1590 2300 2760 3150 3850 4285
In cyclohsxane Wave number 26,450 25,730 25,265 24,860 24,150 23,710 23,280 22 )550
1(F3 mole/l. Analysis
Intensity 7 3 6 8 7 6 5 4
A; 0 720 1185 1590 2300 2740 3170 3900
090 0 0 0 0 0 0 0 0 -
715 1159 1599 1599 1599 1599 1599 1599
x x x
715 1159 2 2 - 715 2 - 1159
strong band at 26,550 cm-r is ascribed to the O,O-band of the system. Vibrational frequencies of 730, 1180 and 1590 cm-l were found. The 1590 cm-1 frequency constituted a main progression and the other frequencies were seen to appear as combination bands with the frequency. The frequencies 730, 1180 and 1590 cm-l [II]
L. A. BRACKWELL,Y. KANDA, and H. SPONER,J. Chews,.Phys. 32, 1465 (1960).
1214
KUNIO TAKEI and YOSRIYA KANDA Table In ethanol
Wave number
lo-3 mole/l.
Intensity
26,340 25,650 25,190 24,750 24,070 23,600 23,170 22,520 22,050
8 4 6 7 6 6 6 5 4
Table In ethanol Wave number 26,500 26,070 25,700 26,320 24,900 24,485 24,110 23,760 23,300 22,900 22,530 22,140 21,720 21,360
10. Phosphorescence
-
AC 0 690 1150 1590 2270 2740 3170 3820 4290
Intensity 10 4 7 8 9 7 8 8 8 7 7 6 5 5
AY” 0 430 800 1180 1600 2015 2390 2740 3200 3600 3970 4360 4780 5140
of m-tolunitrile
In cyclohexane Wave number
10m3mole/l.
Intensity 6 2 4 5 4 4 4 3
spectra
In cyclohexane Wave number
at 90°K
Analysis
26,270 25,580 25,120 24,680 24,030 23,520 23,110 22,420
11. Phosphorescence
1e3 mole/ 1.
spectra
As 0 690 1150 1590 2240 2750 3160 3850
of p-tolunitrile
090
0 0 0 0 0 0 0 0
-
707 1149 1597 1597 1597 1597 1597 1597
x x x
707 1149 2 2 - 707 2 - 1149
at 90°K
1e3 mole/l. Analysis
Intensity
Ay”
26,410
4
0
25,630 25,230 24,810
2 4 6
780 1180 1600
24,050 23,645 23,200
5 4 4
2360 2765 3210
070 0 0 0 0 0 0 0 0 0 0 6 0 0 -
410 819 1194 1604 1604 1604 1604 1604 1604 1604 1604 1604 1604
x x x x x x
410 819 1194 2 2 - 410 2 - 819 2 - 1194 3 3 - 410
correspond to Raman lines 715, 1159 and 1599 cm-l, respectively. They are all assigned to totally symmetric vibrations. The analysis of the spectrum is listed in the last column in Table 9. The analyses of the other isomers in ethanol and in cyclohexane are treated in a similar way. The infrared absorption spectra have also been studied and the results are listed in Table 12, where the ground state frequencies obtained by Raman effect [12], infrared and phosphorescence spectra of tolunitriles are compared. [12] [13] [14] [15]
LANDOLT-B~RNSTAIN, Phys. Chem. Tabell. Dritter ErgLnz.Band 2, 1154 (1935). R. MECKE, Docurnent. MolecuE. Spectra. 3381 Butterworths, London (1958). K. IUSA~I, Bull. Chem. Sot. Japan 11,346 (1936). 9. BARCHEWITZ and M. PARODI, J. phys. radiunz 10,143 (1939).
1215
Phosphorescence spectra of benzonitrile and related compounds Table 12.
Ground-state
meta
para
159 (7)
161 (7)
220 (5) 338 (0) 385 (0.5)
252 (3) 345 (1)
159 167 219 342 385
(4) (8) (4) (1) (1)
457 541 559 590
(8) (6) (1) (3)
459 (3) 522 (4) 576 (1)
410 437 516 549
715 (9) 761 (2)
707 (4)
648 (4) 705 (1)
790 (0) 819 (3)
ortho
meta
para
707 755 795 817 840 865
702 w
704 m 755 w
797 (2) 819 (8)
8 s w w w w
907 w 943 m 980 w
995 (8)
1045 (8)
1042 m
1108 (2)
1109m 1149 (1) 1169 (4)
1172 (10)
w m w m
1036 m 1060 w 1073 w 1094m 1145 w 1165 w
1211 m
1384 m
1225 1236 1281 1315 1380
1460 w 1485 s
1460 w 1487 s
1577 w 1602 m 1625 w
1580 w 1602 m
1288 m 1309 (0) 1378 (2) 1445 (0)
1486 (3) 1571 (3) 1599 (9)
1583 (3) 1597 (4)
1604 (10)
1812 w 1845 w 1890 w
a1
780
a1
908 w 948 w
w w m w m
1019 w 1037 w
1102 w 1120 m 1175m 1195 1210 1272 1288 1308 1383 1412 1450
1510 m 1575 w 1607m
1755 w 1789 w 1810 w 1855 w 1885 w
1185
1150
1180
a1
1590
1590
1600
a1
w w w w w w w w
1695 w 1705 w 1735 w
8
690
para
996 m
1160 m
1245 (4) 1287 (1) 1376 (1)
720
815 s 850 878 896 910
1194 (4) 1209 (10)
1378 (4)
mete
783 s
1020 (0)
1159 (5)
ortho
Symmetry
(4) (1) (0) (3)
896 (1)
991 (1)
Phosphorescence in cyclohexane
Infrared absorption
Raman effect * ortho
vibration frequencies in tolunitriles
KUNIO TAKEI and YOSHIYA KANDA
1216
Table 12
Infra-red absorption
Raman effect * ortho
meta
(Contd)
para
ortho
meta
1927 w
para
Phosphorescence in cyclohexane ortho
meta
Symmetry
para
1920 w 1946 w
2225 (12)
2232 (10)
2228 (10)
2876 (1) 2922 (1)
2877 (0) 2928 (1)
3050 (3) 3070 (2)
3053 (3)
2875 2926 3007 3043
(2) (1) (0) (4)
1965 2150 2225 2300 2850 2910 3018 3050
w s s w w w w w
2230 s
2230 s
2908 w 3020 w
2900 w 3020 w
* See reference [12]. Acknowledgement-The authors wish to express their sincere thanks to Dr. R. SHIMADA in this laboratory for his helpful discussion on this work. Special thanks are also due to Fuji PhotoFilm Company for the generous offer of highly sensitive plates. They are indebted to the Ministry of Education for a grant-in-aid out of the Scientific Research Expenditure.