- Email: [email protected]
The infrared and Raman spectra of pyromellitic dianhydride
Journal ofMolecular Structure, 26 (1975) 297-302 QElsevier Scientific Publishing Company, Amsterdam -
297 Printed in The Netherlands
TIIR INFRARED AND RAMAN SPECTRA OF PYROMELLITIC DIANHYDRIDE
YOSHIYUKI lnstifufo
HASE, KIYOYASU
de &z&mica, Universidade
KAWAI*
and OSWALD0
SALA
de SEo Paula, ScToPaul0 (Brazil)
(Received 9 July 1974)
ABSTKACT The infrared and Raman spectra of solid state samples of pyromellitic dianhydride have been measured. The infrared-Raman mutual exclusion rule has been observed and the frequencies have been tentatively assigned on the basis of Dzh symmetry. The values of the C=O and skeletal ring stretching frequencies have been interpreted in terms of a conjugated n-system. INTRODUCTION
X-ray diffraction [l] has revealed that pyromellitic dianbydride has a quasi-planar structure close to &h symmetry, as shown in Fig. 1.
0
0 ”
fJ$K-j 0
G
0
H 0
Fig. 1. I3,n molecular symmetry of pyromeflitic dianhydride.
The infrared and Raman spectra of pyromeliitic dianhydride have not been reported previously. Considering the selection rules, it seemed of interest to examine the vibrational spectra of this para-tetrasubstituted benzene. Carboxylic anhydrides have been characterized by the band splitting caused by coupling of the C=O stretching vibrations [2] . It is thought that this splitting is due mainly to the electronic nature of the O=C-O-C=O group IS]. For pyromellitic dianhydride, it is to be expecied that the mutual *Permanent address: Faculty of Literature and Science, Toyama University, Toyama, Japan.
exclusion rule and the effect of substitution on the characteristic frequencies associated with the conjugated n-system will yield interesting spectra. EXPERIMENTAL
The pyromellitic dianhydride was obtained commercially. The infrared spectra were recorded from 4000 to 200 cm-‘, using Nujol or hexachloro-1, 3-butadiene mull, on a Perkin-Elmer I.R. 180 spectrophotometer. The Raman spectrum of polycrystalline sample was recorded from 4000 to 35 cm-’ on a Jarrell-Ash Model 25-300 spectrometer using the 4880 A radiation of an argon ion laser for excitation. RESULTS
AND DISCUSSION
The observed frequencies have been tentatively assigned by comparison with the fundamental frequencies of benzene derivatives [4] and carboxylic anhydrides [3, 5-101. As shown in Table 1, the mutual exclusion has definitely been observed in the infrared and Raman spectra, confirming the approximate molecular structure proposed by the X-ray diffraction study [l] . Accordingly, the mutual exclusion rule may be applied to the infrared and Raman spectra of this molecule and there are forty-eight fundamental vibrations of the following species and activities: r = 9ap (R) + 3b,, (R) + 4b,, (R) + 8b,, (R) + 3a, (ia) + 8b,,
(ir) + 8b,,
(ir) + 5b3, (ir). The fundamental vibrations, belonging to ag, bJg, b,, and bIu species, are in-plane modes and the others are out-of-plane modes. The intense band at 3106 cm-’ in the Raman spectrum and the medium band at 3056 cm-’ in the infrared spectrum are assigned to the symmetric and anti-symmetric C-H stretching vibrations, respectively. The observed C=O stretching frequencies are nearly the same as those in other carboxylic anhydrides (e.g., maleic anhydride [3,5,6], phthalic anhydride [9] and mellitic trianhydride [lo] ). The in-phase C=O stretching vibration of the O=C-O-C=O group has been assigned normally to a frequency higher than that of the out-of-phase one [3, 5-101. In the C=O stretching region of the Raman spectrum, two very strong bands, assigned to ag and bSg sp ecies, have been observed at 1872 and 1790 cm-‘, respectively. Also, in the infrared spectrum, two very strong bands, assigned to bzu and b,, species, have been observed at 1854 and 1775 cm-‘, respectively. The band splitting between the in-phase and out-of-phase C=O stretching vibrations of the O=C-O-C=0 group is about 80 cm-‘, nearly the same as found in other carboxylic anhydrides. The difference between two in-phase C=O stretching frequencies, viz., 1872 cm’-* of ag and 1854 cm-’ of bzU, is 18 cm-’ and that between two out-of-phase ones, viz., 1790 cm-’ of bSg and
299
TABLE1 Vibrational
frequencies
and assignments ofpyromellitic dianhydride=
J?requencies(cm-') Baman
Infrared 3669
VW
Assignments ~36
“39
+
3106 s 3102 VW
ag vzgrBz, v397 A,
VI9 + v36 +
3091 VW
v,,, 6,
+
v(C--H)
vl,
3056 m 2996 VW
v(C--HI
vzs, ~JLU
v3
B
2902 VW 2063 VW
~3 + v3.rBz, v,s+ ~29, B3u v(C=O) v,,ag v(C=C) ~36,b,, 2%, A,
1872 vs 1854 vs 1844 VW 1799 VW 1790 vs 1784 VW
+
~23
V3ol
+
~31,
v(c=O) ~41
1775 vs 1724 VW 1703 VW 1686w 1627 vs 1617 VW 1574 w
Ku ~17,
+
~45,
dc=O) v9
~29,
+
%ogl
vzt+
~33,
v32
U33Y
+
1305 vs 1286 w 1276s 1262 w
B,, Ag
v3,
~11
+- v39,
B3u ~37.
bzu
v(c-C)
~30,
b,u
+.
+
~451 +
J33,
~421
vx9a
v(C--cl
v31,bu
v(C--0)
h,
$2)
vg8,
6(C--H)
vzos
1221w
v7
1162 w
VhD + 54 v4*+ 99
~15
1160 VW
v33
1144 w 1132 w
+ +
ag
b,, kg b,
vz1, B,,
B ZLl
V42r
+
b3,
~39.
v46¶
B 29
vs + ~6, J33, v(C--Q
1119 w 1075 m 963vw
B3g
v(=C)
v(c--cl
1172 w
ag
u19y
1238 vs 1229 VW
b,,
1l.l
v(c-c)
~33
1306 m
B
B 1g v(c-C)v,,, b,, ~7 + vg)rBxx VI3 + V45r B 1l.l ~6 + v,s,B3u
v15 +
1342~ 1329s
b3g
B,,
VW--C)
1546 vw 1504 w 1461~ 1441 w 1411 m 1373 m 1345 w
ILl
us,
ag
dC--C)v4o>bm 6(C--HI VE
+
~41,
39
b,u
300 TABLE
1 (continued)
Frequencies Raman 937 VW
804
w
766 755 749
m vs VW
(cm-’ ) Infrared 933 924 912 904 820
vw vs w w VW
798 767
w vs
VW
647 639
vs w
498 m
361 336
w vw
291
vs
734 VW 710 vs
656
VW
635 VW 581 s 567 w 500 VW 488 402 392 364
m VW s m
vs VW w
202
w
191 152
VW w
118 99 75 54 39
w vs vs vs vs
%I
+
y459 %I
r(C-43)
~44, b,,
VS3 + 54 r(C--H) vx3. b,, ua3+ 39 6 (CCC) ~33, b,, 7(C=O)
vlas kg
4C-C)
v,, ag
VIZ+ V4zrB 9U r(C=O) ~459 b,, r(C=O)
~10, kg
h(C=O)
vzz. b,,
s(C=O)
~345
6 WOC)
v7,
6 (CCC)
us,
b,, ag ag
~24 -I- v-,3>B,, 6 (‘XC) vqzab,, VII + V43Y B 31.1 VI6 + V&YB *II 6 (CCC) VZ3¶ b,, 6 (CCC) ~35, b,, v43 + 39 HE-+,’
v,y b,u V,,V b vg, agZU
s(E0) ~47
+
vam
A,
ww
lJai+ 99
ww ww
@(C--c) ~15, b,, ~12 f ~a,,, Bzu V4, + 75
255 213
ww ww
6 (CCC) 2v,,, A, V,, + 54 v4, + 54 YqS+ 75
202
vvw
301 290 281
277 270 255
v(C-0) ~zrr b,, *, + v42, B,, v(C--o) uga, b,,
v-,3 + v.,w B,,
709 w 663
Assignments
13Bb
~249
bag
0(C--c) V,xr b,, @(c-C) ~479 b3u VIZ+ 39 @(C--c) @(C-C)
viz’ b,,
o(C-C)
~16.b:,
Lattice Lattice Lattice Lattice
avs, very strong; s, strong; m, medium; w, weak; vw, very weak and ww, bEstimated from the combination bands.
v4sr
b,u
vibration vibration vibration vibration
very very weak-
301
1775 cm-’ of blu, is 15 cm-‘. These differences are small compared with the splittings between the in-phase and out-of-phase C=O stretching frequencies and may be interpreted in terms of long range interactions caused probably by the conjugated n-system. Three Raman bands at 1627,1574 and 755 cm-’ and three infrared bands at 1411,1373 and 1238 cm-’ are attributable probably to %, b,,, a+,, bzU, bl, and bTUbenzene ring stretching vibrations, respectively. By correlating approximately these six benzene ring stretching vibrational modes with those of phthalic anhydride f9], it was found that for the totally symmetric modes, the frequencies of the dianhydride are about 20-30 cm-’ higher than those of the anhydride (1600 and 735 cm-‘) while for the other four modes, they are about 30-100 cm-’ lower than those of the anhydride (1612,1518, 1471 and 1334 cm-‘); on average, the benzene ring stretching frequencies can be regarded as a shift to lower frequencies. Considering resonance structures for pyromellitic dianhydride and phthalit anhydride, the n-bonding character in the benzene ring of the former is expected to be smaller than that of the latter. The decrease in the benzene ring stretching frequencies can be attributed mainly to this decrease of 7rbonding character. By comparing the C-O-C stretching vibrations of pyromellitie dianhydride with those of maleic anhydride [ 3, 5,6] and phthalic anhydride [9 J , two Raman bands can be assigned at 1305 and 937 cm-’ to the in-phase (%) and out-of-phase (bsg) modes, and two infrared bands at 1276 and 924 cm- ’ to the in-phase (bZU) and out-of-phase (bi,) modes, respectively. These are about 16-46 cm-’ higher in frequency than those of phthalic anhydride, e.g., 1256 and 908 cm- ‘. In aromatic dicarboxylic anhydrides, the increase in the electron density on the O=C-O-C=O group by conjugation with a benzene ring results in a decrease in the contribution of the resonance structures O=C-O+=C-Oand O--C=O+-C=O. This effect, less pronounced in pyromellitic dianhydride than in phthahc anhydride, is expected to raise the C-O-C group frequencies in the former. The assignments of the bands in the region lower than 900 cm-‘, except for some characteristic ones, are rather tentative and will not be discussed. ACKNOWLEDGEMENTS
This work was supported by Funda+o de Amparo B Pesquisa do Estado de Sao Paul0 (FAPESP) and Conselho National de Pesquisas. Y. H. and K. K. wish to thank FAPESP, and K. K. is also grateful to the Organization of American States for financial assistance.
302
REFERENCES 1 J. C. A. Boeyens and F. H. Herbstein, J. Phys. Chem., 69 (1965) 2160. 2 L. J. Bellamy, The Infra-red Spectra of Complex Molecules, Methuen, London, 1954, p. 110. 3 P. Mirone and P. Chiorboli, Spectrochim. Acta, 18 (1962) 1425. 4 G. Varsanyi, Vibrational Spectra of Benzene Derivatives, Academic Press, New York, 1969. 5 C. Di Lauro, S. Caiifano and G. Adembri, J. Mol. Struct., 2 (1968) 173. 6 A. Rogstad, P. Kiaboe, H. Baranska, B. Bjarnov, D. H. Christensen, F. Nicolaisen, 0. F. Nielsen, B. N. Cyvin and S. J. Cyvin, J. Mol. Struct., 20 (1974) 403. 7 A Rogstad, P. Kiaboe, B. N. Cyvin, S. J. Cyvin and D. H. Christensen, Spectrochim. Acta, Part A, 28 (1972) 111. 8 A. Rogstad P. KIaboe, B. N. Cyvin, S. J. Cyvin and D. H. Christensen, Spectrochim. Acta, Part A, 28 (1972) 123. 9 Y. Hase, C. U. Davanzo, K. Kawai and 0. Sala, to be published. 10 Y. Hase and 0. Sala, to be published.
297 Printed in The Netherlands
TIIR INFRARED AND RAMAN SPECTRA OF PYROMELLITIC DIANHYDRIDE
YOSHIYUKI lnstifufo
HASE, KIYOYASU
de &z&mica, Universidade
KAWAI*
and OSWALD0
SALA
de SEo Paula, ScToPaul0 (Brazil)
(Received 9 July 1974)
ABSTKACT The infrared and Raman spectra of solid state samples of pyromellitic dianhydride have been measured. The infrared-Raman mutual exclusion rule has been observed and the frequencies have been tentatively assigned on the basis of Dzh symmetry. The values of the C=O and skeletal ring stretching frequencies have been interpreted in terms of a conjugated n-system. INTRODUCTION
X-ray diffraction [l] has revealed that pyromellitic dianbydride has a quasi-planar structure close to &h symmetry, as shown in Fig. 1.
0
0 ”
fJ$K-j 0
G
0
H 0
Fig. 1. I3,n molecular symmetry of pyromeflitic dianhydride.
The infrared and Raman spectra of pyromeliitic dianhydride have not been reported previously. Considering the selection rules, it seemed of interest to examine the vibrational spectra of this para-tetrasubstituted benzene. Carboxylic anhydrides have been characterized by the band splitting caused by coupling of the C=O stretching vibrations [2] . It is thought that this splitting is due mainly to the electronic nature of the O=C-O-C=O group IS]. For pyromellitic dianhydride, it is to be expecied that the mutual *Permanent address: Faculty of Literature and Science, Toyama University, Toyama, Japan.
exclusion rule and the effect of substitution on the characteristic frequencies associated with the conjugated n-system will yield interesting spectra. EXPERIMENTAL
The pyromellitic dianhydride was obtained commercially. The infrared spectra were recorded from 4000 to 200 cm-‘, using Nujol or hexachloro-1, 3-butadiene mull, on a Perkin-Elmer I.R. 180 spectrophotometer. The Raman spectrum of polycrystalline sample was recorded from 4000 to 35 cm-’ on a Jarrell-Ash Model 25-300 spectrometer using the 4880 A radiation of an argon ion laser for excitation. RESULTS
AND DISCUSSION
The observed frequencies have been tentatively assigned by comparison with the fundamental frequencies of benzene derivatives [4] and carboxylic anhydrides [3, 5-101. As shown in Table 1, the mutual exclusion has definitely been observed in the infrared and Raman spectra, confirming the approximate molecular structure proposed by the X-ray diffraction study [l] . Accordingly, the mutual exclusion rule may be applied to the infrared and Raman spectra of this molecule and there are forty-eight fundamental vibrations of the following species and activities: r = 9ap (R) + 3b,, (R) + 4b,, (R) + 8b,, (R) + 3a, (ia) + 8b,,
(ir) + 8b,,
(ir) + 5b3, (ir). The fundamental vibrations, belonging to ag, bJg, b,, and bIu species, are in-plane modes and the others are out-of-plane modes. The intense band at 3106 cm-’ in the Raman spectrum and the medium band at 3056 cm-’ in the infrared spectrum are assigned to the symmetric and anti-symmetric C-H stretching vibrations, respectively. The observed C=O stretching frequencies are nearly the same as those in other carboxylic anhydrides (e.g., maleic anhydride [3,5,6], phthalic anhydride [9] and mellitic trianhydride [lo] ). The in-phase C=O stretching vibration of the O=C-O-C=O group has been assigned normally to a frequency higher than that of the out-of-phase one [3, 5-101. In the C=O stretching region of the Raman spectrum, two very strong bands, assigned to ag and bSg sp ecies, have been observed at 1872 and 1790 cm-‘, respectively. Also, in the infrared spectrum, two very strong bands, assigned to bzu and b,, species, have been observed at 1854 and 1775 cm-‘, respectively. The band splitting between the in-phase and out-of-phase C=O stretching vibrations of the O=C-O-C=0 group is about 80 cm-‘, nearly the same as found in other carboxylic anhydrides. The difference between two in-phase C=O stretching frequencies, viz., 1872 cm’-* of ag and 1854 cm-’ of bzU, is 18 cm-’ and that between two out-of-phase ones, viz., 1790 cm-’ of bSg and
299
TABLE1 Vibrational
frequencies
and assignments ofpyromellitic dianhydride=
J?requencies(cm-') Baman
Infrared 3669
VW
Assignments ~36
“39
+
3106 s 3102 VW
ag vzgrBz, v397 A,
VI9 + v36 +
3091 VW
v,,, 6,
+
v(C--H)
vl,
3056 m 2996 VW
v(C--HI
vzs, ~JLU
v3
B
2902 VW 2063 VW
~3 + v3.rBz, v,s+ ~29, B3u v(C=O) v,,ag v(C=C) ~36,b,, 2%, A,
1872 vs 1854 vs 1844 VW 1799 VW 1790 vs 1784 VW
+
~23
V3ol
+
~31,
v(c=O) ~41
1775 vs 1724 VW 1703 VW 1686w 1627 vs 1617 VW 1574 w
Ku ~17,
+
~45,
dc=O) v9
~29,
+
%ogl
vzt+
~33,
v32
U33Y
+
1305 vs 1286 w 1276s 1262 w
B,, Ag
v3,
~11
+- v39,
B3u ~37.
bzu
v(c-C)
~30,
b,u
+.
+
~451 +
J33,
~421
vx9a
v(C--cl
v31,bu
v(C--0)
h,
$2)
vg8,
6(C--H)
vzos
1221w
v7
1162 w
VhD + 54 v4*+ 99
~15
1160 VW
v33
1144 w 1132 w
+ +
ag
b,, kg b,
vz1, B,,
B ZLl
V42r
+
b3,
~39.
v46¶
B 29
vs + ~6, J33, v(C--Q
1119 w 1075 m 963vw
B3g
v(=C)
v(c--cl
1172 w
ag
u19y
1238 vs 1229 VW
b,,
1l.l
v(c-c)
~33
1306 m
B
B 1g v(c-C)v,,, b,, ~7 + vg)rBxx VI3 + V45r B 1l.l ~6 + v,s,B3u
v15 +
1342~ 1329s
b3g
B,,
VW--C)
1546 vw 1504 w 1461~ 1441 w 1411 m 1373 m 1345 w
ILl
us,
ag
dC--C)v4o>bm 6(C--HI VE
+
~41,
39
b,u
300 TABLE
1 (continued)
Frequencies Raman 937 VW
804
w
766 755 749
m vs VW
(cm-’ ) Infrared 933 924 912 904 820
vw vs w w VW
798 767
w vs
VW
647 639
vs w
498 m
361 336
w vw
291
vs
734 VW 710 vs
656
VW
635 VW 581 s 567 w 500 VW 488 402 392 364
m VW s m
vs VW w
202
w
191 152
VW w
118 99 75 54 39
w vs vs vs vs
%I
+
y459 %I
r(C-43)
~44, b,,
VS3 + 54 r(C--H) vx3. b,, ua3+ 39 6 (CCC) ~33, b,, 7(C=O)
vlas kg
4C-C)
v,, ag
VIZ+ V4zrB 9U r(C=O) ~459 b,, r(C=O)
~10, kg
h(C=O)
vzz. b,,
s(C=O)
~345
6 WOC)
v7,
6 (CCC)
us,
b,, ag ag
~24 -I- v-,3>B,, 6 (‘XC) vqzab,, VII + V43Y B 31.1 VI6 + V&YB *II 6 (CCC) VZ3¶ b,, 6 (CCC) ~35, b,, v43 + 39 HE-+,’
v,y b,u V,,V b vg, agZU
s(E0) ~47
+
vam
A,
ww
lJai+ 99
ww ww
@(C--c) ~15, b,, ~12 f ~a,,, Bzu V4, + 75
255 213
ww ww
6 (CCC) 2v,,, A, V,, + 54 v4, + 54 YqS+ 75
202
vvw
301 290 281
277 270 255
v(C-0) ~zrr b,, *, + v42, B,, v(C--o) uga, b,,
v-,3 + v.,w B,,
709 w 663
Assignments
13Bb
~249
bag
0(C--c) V,xr b,, @(c-C) ~479 b3u VIZ+ 39 @(C--c) @(C-C)
viz’ b,,
o(C-C)
~16.b:,
Lattice Lattice Lattice Lattice
avs, very strong; s, strong; m, medium; w, weak; vw, very weak and ww, bEstimated from the combination bands.
v4sr
b,u
vibration vibration vibration vibration
very very weak-
301
1775 cm-’ of blu, is 15 cm-‘. These differences are small compared with the splittings between the in-phase and out-of-phase C=O stretching frequencies and may be interpreted in terms of long range interactions caused probably by the conjugated n-system. Three Raman bands at 1627,1574 and 755 cm-’ and three infrared bands at 1411,1373 and 1238 cm-’ are attributable probably to %, b,,, a+,, bzU, bl, and bTUbenzene ring stretching vibrations, respectively. By correlating approximately these six benzene ring stretching vibrational modes with those of phthalic anhydride f9], it was found that for the totally symmetric modes, the frequencies of the dianhydride are about 20-30 cm-’ higher than those of the anhydride (1600 and 735 cm-‘) while for the other four modes, they are about 30-100 cm-’ lower than those of the anhydride (1612,1518, 1471 and 1334 cm-‘); on average, the benzene ring stretching frequencies can be regarded as a shift to lower frequencies. Considering resonance structures for pyromellitic dianhydride and phthalit anhydride, the n-bonding character in the benzene ring of the former is expected to be smaller than that of the latter. The decrease in the benzene ring stretching frequencies can be attributed mainly to this decrease of 7rbonding character. By comparing the C-O-C stretching vibrations of pyromellitie dianhydride with those of maleic anhydride [ 3, 5,6] and phthalic anhydride [9 J , two Raman bands can be assigned at 1305 and 937 cm-’ to the in-phase (%) and out-of-phase (bsg) modes, and two infrared bands at 1276 and 924 cm- ’ to the in-phase (bZU) and out-of-phase (bi,) modes, respectively. These are about 16-46 cm-’ higher in frequency than those of phthalic anhydride, e.g., 1256 and 908 cm- ‘. In aromatic dicarboxylic anhydrides, the increase in the electron density on the O=C-O-C=O group by conjugation with a benzene ring results in a decrease in the contribution of the resonance structures O=C-O+=C-Oand O--C=O+-C=O. This effect, less pronounced in pyromellitic dianhydride than in phthahc anhydride, is expected to raise the C-O-C group frequencies in the former. The assignments of the bands in the region lower than 900 cm-‘, except for some characteristic ones, are rather tentative and will not be discussed. ACKNOWLEDGEMENTS
This work was supported by Funda+o de Amparo B Pesquisa do Estado de Sao Paul0 (FAPESP) and Conselho National de Pesquisas. Y. H. and K. K. wish to thank FAPESP, and K. K. is also grateful to the Organization of American States for financial assistance.
302
REFERENCES 1 J. C. A. Boeyens and F. H. Herbstein, J. Phys. Chem., 69 (1965) 2160. 2 L. J. Bellamy, The Infra-red Spectra of Complex Molecules, Methuen, London, 1954, p. 110. 3 P. Mirone and P. Chiorboli, Spectrochim. Acta, 18 (1962) 1425. 4 G. Varsanyi, Vibrational Spectra of Benzene Derivatives, Academic Press, New York, 1969. 5 C. Di Lauro, S. Caiifano and G. Adembri, J. Mol. Struct., 2 (1968) 173. 6 A. Rogstad, P. Kiaboe, H. Baranska, B. Bjarnov, D. H. Christensen, F. Nicolaisen, 0. F. Nielsen, B. N. Cyvin and S. J. Cyvin, J. Mol. Struct., 20 (1974) 403. 7 A Rogstad, P. Kiaboe, B. N. Cyvin, S. J. Cyvin and D. H. Christensen, Spectrochim. Acta, Part A, 28 (1972) 111. 8 A. Rogstad P. KIaboe, B. N. Cyvin, S. J. Cyvin and D. H. Christensen, Spectrochim. Acta, Part A, 28 (1972) 123. 9 Y. Hase, C. U. Davanzo, K. Kawai and 0. Sala, to be published. 10 Y. Hase and 0. Sala, to be published.