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Single crystal ODMR and phosphorescence studies of the 3nπ* state of aliphatic carbonyl: 2-indanone
Volume 64, number 2
CHEMICAL PHYSICS LE?TERS
1 Jufy 1979
SINGLE CRYSTAL ODMR AND PHOSPHORESCENCE STUDIES OF THE 3nn* STATE OF ALIPHATIC CARBONYL: ZINDANONE Masaaki BABA and Noboru HIROTA Deparrment A-J oto
of Cizemistq. Faculty
*
of Science,
ACpwo
Unirersiry.
606. hparz
Received 1 April 1979
We have made single crystal ODOR and phosphorescence studies of the T1 state of 2-indanone. It was shown that the T, state of 2-indanone is very similar to that of the ‘nd state cyclopentanone_ The well resolved phosphorescence specl m indicates that the 3nd 2-indanone has a distorted structure_ A proposed decay scheme was confirmed from a single crystal ODhlR study at low magnetic field.
l_ Introduction Over the last ten years, ODIMR technique has been used very successfully in elucidating the properties of the Iowest excited trip!et (T, j states of aromatic carbonyls such as benzophenone [l-4], benzaldehyde [S-7] and benzoquinone [8,9] _ On the other hand, there have been only a few ODMR studies of the 3nn* states of aliphatic carbonyls. Understanding of the properties of the 3nrr* states of simpIe aliphatic carbonyls is important in several points_ For example, there has been considerable interest in the zero field splittings (ZFS’s) and decay properties of simple carbonyls such 2s formaldehyde [IO] _Aliphatic c2rbonyls are known to have pyramidal structures in the 3nirf states [I I-14) in contrast to nearly planar structures of the 3nir* states of aromatic c2rbonyls [I 5] _ It is important to know how the ZFS’s 2nd decay properties are affected by the structuml changes. Shain, Chiang and Sharnoff were the fast to investigate the 3nrr* aliphatic carbonyl by ODMR [1618]_ They investigated the 3nn* state of cycIopentanone, but their studies were Iimited to polycrysmlhne or glass samples 2nd their interpretation of the data is not free from ambiguities_ It is thus desirable to * Also at: Department of Chemistry. State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
make detailed single crystal ODMR studies of the 3nrr* aliphatic carbonyls. We found that the T1 state of Z-indanone is very similar to the 3nrr* state of cyclopentanone 2nd can be used 2s a model to study 3n,;* aliphatic carbonyls. Since z-indanone gives an unusually well resolved phosphorescence spectrum 2nd can be studied in single crystals, we have undertaken single crystal ODMR and phosphorescence studies of the T, state of %ndanone_ Our results suggest that the subIeve1 scheme previously proposed by Sharnoff et aI_ should be reconside&d.
2. Experimental We have investigated 2-indanone in the dtirene mixed crystal 2nd in the neat crystal. For the sake of comparison we 2Is.o studied the phosphorescence of the neat crystal of cyclopentanone. 2-in&none (Aldrich) was purified by repeated vacuum sublimations. Durene was purified by extensive zone refting after recrystallization from ethanol. Cyclopentanone was purified by vacuum distillation. Single crysta& were grown by ihe standard Bridgman method. In order to make a cyclopentanone neat crystal a dry iceethanol bath was used_ In fig_ 1, we give the mclecular structure and the axis systems used in this paper. 321
Volume64, number2
2-1NoANoNE
iXJRfNf ET%. f. RIolecuIar
CHEMICALPHYSKZ!jLETTERS
Nucture
and the axissystemusedhere-
Phosphorescence spectra were taken with a Spes 1704 scanning spectrometer at 42 K and I.5 K. Zero field ODIIR experiments were made using a setup very similar to that already described before [ 191. We followed the procedure given in ref- [ZOJ_ in order to do low field OD&ZR experiments the LiquidIieIium cryostat containing a microwave helix wx placed between the pofes of rzn electromagnet_ Si~gIe crystal samples were mounted in the hei& in the desired orientation with the aid of a polarizing microscope. The ODM R sign& were obtained by detecting the phosphorescence at 404 nm and sweeping the microwave sweeper nt O-7 GFfi/s_ Si~nais were recorded after averagingabout 200 times.
450
400
3_ Results and disctz&m The phosphorescence spectrum of the 2-indanone neat crystal is shown in fig. 2a. This spectrum is very different from those of 3n~* aromatic carbonyls such as 1-indanone j2I]_ III fig_ 2b the phosphorescence spectrum of cyclopentanone is shown for comparison- Though the resolution of the cyclopentanone spectrum is poor, it is seen that both spectra are very &m&r_ These observations indicate that the T1 state of2-indanone is essentiaily the same as that of cyclopentanone, Both spectra are characterized by extremely weak O-O bands and long progressions of about 430 cm-l vibration which is assigned to the C=O wag_ The 3nii4 state of cyclopentanone is known to have a pyramidal structure in the gz phase [22] and the spectral features obtained here indicate that the TX states of both Xndarrone and cydopentanone ako have distorted structures in ihe crystalline systems_ Under expanded high resoIution 2-irtdanone neat crystal gives a well resolved spectrum shown in fig. 2c. The O-O band is located at 3464 A (28868
cIIl--1).
p-ii-2. Phosphorescence spectraof 6) %ndanone and (b) eyclopentanolre neatcrystjfsat 4.2 K- fc) FirstthreeSOUPS orpezks of the expandedhighresoIution phosphorescence spectrumof 2-indznoneneat~a& 2-indanone in durene and neat crystab give very strong ODM R signals at 2-i 5 and 2_S3 GHz. These transition frequencies are not very different from I .625 and 3394 GHz found for cyclopentanone f18] _ Two of the sublevels (top and bottom) are radiatively active and very short-lived (about 3 ms Iifetime). The other (middle) subkvel has a reIatively long Iife-
time (80 ms). This decay characteristic is very similar to that of cyclopentanone, though the two fast decaying sublevels of cycfopentanone have considerably shorter Lifetimes_‘Eke results of the ODOR studies are summarized in tables f and 2_ Znthe following diScussion we use the axis system given in fig_ f _ In a nearly planar 3nn* aromatic carbony1 the most radiative sublevel is known to be the z sublevel when the L axis is taken parallel to the C=O direction [I-5] _ The other sublevels are radiativeiy
Volume
64, number 2
CHEMICAL
PHYSICS
LElTERS
I July 1979
Table 1 Spectroscopic
data
___-
___--
-___-___
2-indanone neat crystal phosphorescence O-O band (cm-‘)
---
28868
2indanone in durene ~_
Cyclopentanone al
28727
28860
2.154 2.829
transition X-Y frequency (GHz) Y - 2 ZFS IDI parameter (cm-r) [El __~_ _~_---~
0.1302 0.0360
__-
1.625 3.397
2.157 2.825
0.1303 0.0359 __ _- _----_____~_-_.
-_-
-
__ -
0.1403 0.027 1
__
a) Data for eydopentanone were taken from ref. Il7]_ Table 2 Decay data
--X Y
z
-2-indanone neat crystal --.-_.
--_-
ki 270
13.0
254
-I_
--
X-f
-_____
0.31
0.07 1
--Cyclopentanone 3
2-indanone in durene ki
k; ___ _______ _ __
262 12.2 249
0.28
--
ki ___ __-___775
0.47
79.4
1
x-i
725
0.017 1
al Data for cyclopentanone were taken from ref. [ 171.
inactive comparatively_ The z sublevel of the ahphatic carbonyl is aIso expected to be radiatively active, since the z sublevel of the 3nz’ state effectively couples with the ‘rrrr* state via spin-orbit coupling [ IO.231 _ Theoretical caicuiations on planar formaldehyde predict that the x sublevel is also rather radiatively active [ 10,24,25] _Furthermore the Tl state of 2-indanone as well as that of cyclopentanone is distorted from the planar structure as the phosphorescence spectrum indicates. If an ahphatic carbonyl has a pyramidal structure (C,), the _x direction may no longer be perpendictdar to the C=Cl direct&. This also makes the x sublevei radiative_ The experimenta! resuIt on 2indanone that two sublevels (top and bottom) are radiativeIy active bears out this expectation_ We tentatively assume that the most radiative sublevel is the a sublevel_ However, the present experiments cannot decide Whether the z sublevel is the top or the bottom. Accordingly, the sublevel scheme expected from the decay characteristic is either (a) or (b) shown in fig. 3. The ZFSs obtained from these sublevel schemes are
IOI = 0.1303,
IEI = 0.0359
cm-l
for 2-indanone and for cycIopentanone_ The present sublevel scheme is, however, not in ageement with the scheme previously suggested by Sharnoff et al. from the analysis of the partially resolved hyperfine structures_ They suggested that they sublevel is the radiatively active one in cyclopentanone_ This assignment gives the schemes shown in figs_ 3c and 3d_ in order to confirm the sublevel scheme, we have made a singe crystar ODOR study at low magnetic field. In the durene crystal there are two molecules per unit ceII which occupy two different sites [26] _The short (M) axes of both types of molecules are nearly perpendicular to the cieavage pIane_ In the mixed crystal 2-indanone is expected to replace durene with they axis nearly paraIIe1 to the M axis of durene. When we apply the magnetic field perpendicular to the cleavage plane, the magnetic field becomes approsimately paraIIe1 to they directions of 2-indanones in two sites. In fig 3e we present the observed field dependence of tne ODOR transition frequencies_ Both of the transi-
lOi= 0.1403,lEf= 0.0271 cm-l
323
Vohrrne 64. nurrber 2
CHEhfICAL
PHYSICS LETTERS
1 July 1979
Acknowledgement This research was supported in part by a grant from the Ministry of Education of Japan.
References [ 1 I WX Veeman and J.JJ_ van der Wzds. Chem_ Phys. Letters 7 (1970) 65. [2I M_Shamoff turd E-B_ Iturbe, J_ Chem_ Phys. 62 (1975)
Fz_ 3_ Mzgnetic field (H I 13 dependence of the ODMR lignS The open chctes indimte the frequency of the observed peahs, s&id line-krdicates the field dependence of the resonance frequencies cakuhrted us@ the ZFS values given in table 1 and ZFS scheme (a) cr (b). Dzhed line is the one c&xthted with
scheme (c) or (d)_ tion frequencies are shifted upward upon application of the magnetic field_ Tbis rest& is consistently e-xplained witb our sublevel scheme_ It is not possible to explain the result using scheme (c) or (d) as Iong ns Z-indanone goes into durene crystal with itsy axis approximately pardIe to the LV axis of durene_ It is considered tktt this subIeve1 scheme is also appIicabIe to cyclopentanoneIt is interesting to note that the ZFS’s of the 3nn* 2-indanone and cyciopentanone are rather smaH. Recent WO& by RrtmsnV et aI. aLso gives a small v&e of D for form;rJdebyde 127] (IOI = O-141 cm-‘) different from tire nther Iarge value ([D J = 0.36 cm-‘) originaMy given by Raynes 1121. On the other hand, the ab initio calculation of formaldehyde based on a phnar structure gives e large vnIue of O[ 1 O] in disagreement witlt Ramys value_ CaIcuJations of ZFSs for aIipJwtic carbonyls with bent structures seem to be in need. Further detaiis of the ODOR and phosphorescence studies of Z-indanone wiII be reported Inter_ 324
145. [3 ] JA hfucha and D-N’_ Pratt. J_ Chem_ Phys. 66 (1977) 5339_ [4] R&f- Hochstrasser, G-W_ Scott and A.H. ZewaiI, hfol. Phyr 36 (1978) 475. (51 T-H_ Cheng and N_ Hirota. hfol.Phys. 27 (1974) 281_ [6I E-T_ Hnrrigan and N_ Hirotz, hfoL Phyr 31 (1976) 663, 681_ 171 A- %Iurmna and D.S. TiMi, Chem. J’hys. Letters 13 (1972) 278. [8I H_ VecnvIiet and D-A_ Wiersma, Chem_ Phys. 8 (1975) 432. [91 BJL Loo snd Ii. kuuis, J. Chem_ Phys. 65 (1976) 5076_ (IO ] S-R_ Langhoff and E-R- Davidson, J. Chem. Phys. 64 (1976) 4699, and references therein. [II j J.CD_ Brand, J. Chen Sot_ (1956) 858_ 1121 W-T_ Raynes. J_ Chem Phys_ 44 (1966) 27%. I1 31 _ _ L-E- Giddincs Jr_ md KX- Innes. J. hfol Sue&-v. _ _~36 (1970) 53. (141 G-W- Robinson and V-E. DiGiorgio, Can. J_ Chem. 36 (1958) 31_ [15: A. Nishimura and 1. Vincent, Cbem. Phys. Letters 13 (1972) 89. [16] AL. ShGn, W-T. Chtig and hf_ Sbamoff, Chem- PhysLetters 15 (1972) 2136~ 1171 A-L. Shaln and hf_ Sharnoff, Chem_ Phys. Letters 16 (1972) 503. [18l A-L. Shah and hf. Shamoff, Chem_ Phys. Letters 22 (1973) 56_ [191 T-H. Cheng and N_ Hirota, J_ Chem. Phys. 56 (1972) 5019. [2OI J. Schmidt, WS- Veeman and J-H_ van der Waak, Chem. Phys. Letters 4 (1969) 341_ &?I 1 S. Niizuma and N- Hirota, J. Phys- Chem. 82 (1978) 453. f22] HE. Howard-Lock and G-W_ King. -~ J_ MoL Spectry. 36 (1970) 53. I231 J-W- Sidman, J. Cbem Phys. 29 (1958) 644_ 1241 R.L. ElIis. R_ Squire and H_H_ Jaffe. J_ Chem. Phvs- 5.5 _ (1971) 3499. I251 G-L- Bendazzoli and P. PaImieri, Intern. J. Quantum Chem. 8 (1974) 941. 1261 J-M- Robertson, Proc_ Roy. Sot A141 (1933) 594. 1271 E-W- Bim, R-Y- Dong nnd D.A. Ramsay, Chem. Phys.
Letters 18 <1973>11_
CHEMICAL PHYSICS LE?TERS
1 Jufy 1979
SINGLE CRYSTAL ODMR AND PHOSPHORESCENCE STUDIES OF THE 3nn* STATE OF ALIPHATIC CARBONYL: ZINDANONE Masaaki BABA and Noboru HIROTA Deparrment A-J oto
of Cizemistq. Faculty
*
of Science,
ACpwo
Unirersiry.
606. hparz
Received 1 April 1979
We have made single crystal ODOR and phosphorescence studies of the T1 state of 2-indanone. It was shown that the T, state of 2-indanone is very similar to that of the ‘nd state cyclopentanone_ The well resolved phosphorescence specl m indicates that the 3nd 2-indanone has a distorted structure_ A proposed decay scheme was confirmed from a single crystal ODhlR study at low magnetic field.
l_ Introduction Over the last ten years, ODIMR technique has been used very successfully in elucidating the properties of the Iowest excited trip!et (T, j states of aromatic carbonyls such as benzophenone [l-4], benzaldehyde [S-7] and benzoquinone [8,9] _ On the other hand, there have been only a few ODMR studies of the 3nn* states of aliphatic carbonyls. Understanding of the properties of the 3nrr* states of simpIe aliphatic carbonyls is important in several points_ For example, there has been considerable interest in the zero field splittings (ZFS’s) and decay properties of simple carbonyls such 2s formaldehyde [IO] _Aliphatic c2rbonyls are known to have pyramidal structures in the 3nirf states [I I-14) in contrast to nearly planar structures of the 3nir* states of aromatic c2rbonyls [I 5] _ It is important to know how the ZFS’s 2nd decay properties are affected by the structuml changes. Shain, Chiang and Sharnoff were the fast to investigate the 3nrr* aliphatic carbonyl by ODMR [1618]_ They investigated the 3nn* state of cycIopentanone, but their studies were Iimited to polycrysmlhne or glass samples 2nd their interpretation of the data is not free from ambiguities_ It is thus desirable to * Also at: Department of Chemistry. State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
make detailed single crystal ODMR studies of the 3nrr* aliphatic carbonyls. We found that the T1 state of Z-indanone is very similar to the 3nrr* state of cyclopentanone 2nd can be used 2s a model to study 3n,;* aliphatic carbonyls. Since z-indanone gives an unusually well resolved phosphorescence spectrum 2nd can be studied in single crystals, we have undertaken single crystal ODMR and phosphorescence studies of the T, state of %ndanone_ Our results suggest that the subIeve1 scheme previously proposed by Sharnoff et aI_ should be reconside&d.
2. Experimental We have investigated 2-indanone in the dtirene mixed crystal 2nd in the neat crystal. For the sake of comparison we 2Is.o studied the phosphorescence of the neat crystal of cyclopentanone. 2-in&none (Aldrich) was purified by repeated vacuum sublimations. Durene was purified by extensive zone refting after recrystallization from ethanol. Cyclopentanone was purified by vacuum distillation. Single crysta& were grown by ihe standard Bridgman method. In order to make a cyclopentanone neat crystal a dry iceethanol bath was used_ In fig_ 1, we give the mclecular structure and the axis systems used in this paper. 321
Volume64, number2
2-1NoANoNE
iXJRfNf ET%. f. RIolecuIar
CHEMICALPHYSKZ!jLETTERS
Nucture
and the axissystemusedhere-
Phosphorescence spectra were taken with a Spes 1704 scanning spectrometer at 42 K and I.5 K. Zero field ODIIR experiments were made using a setup very similar to that already described before [ 191. We followed the procedure given in ref- [ZOJ_ in order to do low field OD&ZR experiments the LiquidIieIium cryostat containing a microwave helix wx placed between the pofes of rzn electromagnet_ Si~gIe crystal samples were mounted in the hei& in the desired orientation with the aid of a polarizing microscope. The ODM R sign& were obtained by detecting the phosphorescence at 404 nm and sweeping the microwave sweeper nt O-7 GFfi/s_ Si~nais were recorded after averagingabout 200 times.
450
400
3_ Results and disctz&m The phosphorescence spectrum of the 2-indanone neat crystal is shown in fig. 2a. This spectrum is very different from those of 3n~* aromatic carbonyls such as 1-indanone j2I]_ III fig_ 2b the phosphorescence spectrum of cyclopentanone is shown for comparison- Though the resolution of the cyclopentanone spectrum is poor, it is seen that both spectra are very &m&r_ These observations indicate that the T1 state of2-indanone is essentiaily the same as that of cyclopentanone, Both spectra are characterized by extremely weak O-O bands and long progressions of about 430 cm-l vibration which is assigned to the C=O wag_ The 3nii4 state of cyclopentanone is known to have a pyramidal structure in the gz phase [22] and the spectral features obtained here indicate that the TX states of both Xndarrone and cydopentanone ako have distorted structures in ihe crystalline systems_ Under expanded high resoIution 2-irtdanone neat crystal gives a well resolved spectrum shown in fig. 2c. The O-O band is located at 3464 A (28868
cIIl--1).
p-ii-2. Phosphorescence spectraof 6) %ndanone and (b) eyclopentanolre neatcrystjfsat 4.2 K- fc) FirstthreeSOUPS orpezks of the expandedhighresoIution phosphorescence spectrumof 2-indznoneneat~a& 2-indanone in durene and neat crystab give very strong ODM R signals at 2-i 5 and 2_S3 GHz. These transition frequencies are not very different from I .625 and 3394 GHz found for cyclopentanone f18] _ Two of the sublevels (top and bottom) are radiatively active and very short-lived (about 3 ms Iifetime). The other (middle) subkvel has a reIatively long Iife-
time (80 ms). This decay characteristic is very similar to that of cyclopentanone, though the two fast decaying sublevels of cycfopentanone have considerably shorter Lifetimes_‘Eke results of the ODOR studies are summarized in tables f and 2_ Znthe following diScussion we use the axis system given in fig_ f _ In a nearly planar 3nn* aromatic carbony1 the most radiative sublevel is known to be the z sublevel when the L axis is taken parallel to the C=O direction [I-5] _ The other sublevels are radiativeiy
Volume
64, number 2
CHEMICAL
PHYSICS
LElTERS
I July 1979
Table 1 Spectroscopic
data
___-
___--
-___-___
2-indanone neat crystal phosphorescence O-O band (cm-‘)
---
28868
2indanone in durene ~_
Cyclopentanone al
28727
28860
2.154 2.829
transition X-Y frequency (GHz) Y - 2 ZFS IDI parameter (cm-r) [El __~_ _~_---~
0.1302 0.0360
__-
1.625 3.397
2.157 2.825
0.1303 0.0359 __ _- _----_____~_-_.
-_-
-
__ -
0.1403 0.027 1
__
a) Data for eydopentanone were taken from ref. Il7]_ Table 2 Decay data
--X Y
z
-2-indanone neat crystal --.-_.
--_-
ki 270
13.0
254
-I_
--
X-f
-_____
0.31
0.07 1
--Cyclopentanone 3
2-indanone in durene ki
k; ___ _______ _ __
262 12.2 249
0.28
--
ki ___ __-___775
0.47
79.4
1
x-i
725
0.017 1
al Data for cyclopentanone were taken from ref. [ 171.
inactive comparatively_ The z sublevel of the ahphatic carbonyl is aIso expected to be radiatively active, since the z sublevel of the 3nz’ state effectively couples with the ‘rrrr* state via spin-orbit coupling [ IO.231 _ Theoretical caicuiations on planar formaldehyde predict that the x sublevel is also rather radiatively active [ 10,24,25] _Furthermore the Tl state of 2-indanone as well as that of cyclopentanone is distorted from the planar structure as the phosphorescence spectrum indicates. If an ahphatic carbonyl has a pyramidal structure (C,), the _x direction may no longer be perpendictdar to the C=Cl direct&. This also makes the x sublevei radiative_ The experimenta! resuIt on 2indanone that two sublevels (top and bottom) are radiativeIy active bears out this expectation_ We tentatively assume that the most radiative sublevel is the a sublevel_ However, the present experiments cannot decide Whether the z sublevel is the top or the bottom. Accordingly, the sublevel scheme expected from the decay characteristic is either (a) or (b) shown in fig. 3. The ZFSs obtained from these sublevel schemes are
IOI = 0.1303,
IEI = 0.0359
cm-l
for 2-indanone and for cycIopentanone_ The present sublevel scheme is, however, not in ageement with the scheme previously suggested by Sharnoff et al. from the analysis of the partially resolved hyperfine structures_ They suggested that they sublevel is the radiatively active one in cyclopentanone_ This assignment gives the schemes shown in figs_ 3c and 3d_ in order to confirm the sublevel scheme, we have made a singe crystar ODOR study at low magnetic field. In the durene crystal there are two molecules per unit ceII which occupy two different sites [26] _The short (M) axes of both types of molecules are nearly perpendicular to the cieavage pIane_ In the mixed crystal 2-indanone is expected to replace durene with they axis nearly paraIIe1 to the M axis of durene. When we apply the magnetic field perpendicular to the cleavage plane, the magnetic field becomes approsimately paraIIe1 to they directions of 2-indanones in two sites. In fig 3e we present the observed field dependence of tne ODOR transition frequencies_ Both of the transi-
lOi= 0.1403,lEf= 0.0271 cm-l
323
Vohrrne 64. nurrber 2
CHEhfICAL
PHYSICS LETTERS
1 July 1979
Acknowledgement This research was supported in part by a grant from the Ministry of Education of Japan.
References [ 1 I WX Veeman and J.JJ_ van der Wzds. Chem_ Phys. Letters 7 (1970) 65. [2I M_Shamoff turd E-B_ Iturbe, J_ Chem_ Phys. 62 (1975)
Fz_ 3_ Mzgnetic field (H I 13 dependence of the ODMR lignS The open chctes indimte the frequency of the observed peahs, s&id line-krdicates the field dependence of the resonance frequencies cakuhrted us@ the ZFS values given in table 1 and ZFS scheme (a) cr (b). Dzhed line is the one c&xthted with
scheme (c) or (d)_ tion frequencies are shifted upward upon application of the magnetic field_ Tbis rest& is consistently e-xplained witb our sublevel scheme_ It is not possible to explain the result using scheme (c) or (d) as Iong ns Z-indanone goes into durene crystal with itsy axis approximately pardIe to the LV axis of durene_ It is considered tktt this subIeve1 scheme is also appIicabIe to cyclopentanoneIt is interesting to note that the ZFS’s of the 3nn* 2-indanone and cyciopentanone are rather smaH. Recent WO& by RrtmsnV et aI. aLso gives a small v&e of D for form;rJdebyde 127] (IOI = O-141 cm-‘) different from tire nther Iarge value ([D J = 0.36 cm-‘) originaMy given by Raynes 1121. On the other hand, the ab initio calculation of formaldehyde based on a phnar structure gives e large vnIue of O[ 1 O] in disagreement witlt Ramys value_ CaIcuJations of ZFSs for aIipJwtic carbonyls with bent structures seem to be in need. Further detaiis of the ODOR and phosphorescence studies of Z-indanone wiII be reported Inter_ 324
145. [3 ] JA hfucha and D-N’_ Pratt. J_ Chem_ Phys. 66 (1977) 5339_ [4] R&f- Hochstrasser, G-W_ Scott and A.H. ZewaiI, hfol. Phyr 36 (1978) 475. (51 T-H_ Cheng and N_ Hirota. hfol.Phys. 27 (1974) 281_ [6I E-T_ Hnrrigan and N_ Hirotz, hfoL Phyr 31 (1976) 663, 681_ 171 A- %Iurmna and D.S. TiMi, Chem. J’hys. Letters 13 (1972) 278. [8I H_ VecnvIiet and D-A_ Wiersma, Chem_ Phys. 8 (1975) 432. [91 BJL Loo snd Ii. kuuis, J. Chem_ Phys. 65 (1976) 5076_ (IO ] S-R_ Langhoff and E-R- Davidson, J. Chem. Phys. 64 (1976) 4699, and references therein. [II j J.CD_ Brand, J. Chen Sot_ (1956) 858_ 1121 W-T_ Raynes. J_ Chem Phys_ 44 (1966) 27%. I1 31 _ _ L-E- Giddincs Jr_ md KX- Innes. J. hfol Sue&-v. _ _~36 (1970) 53. (141 G-W- Robinson and V-E. DiGiorgio, Can. J_ Chem. 36 (1958) 31_ [15: A. Nishimura and 1. Vincent, Cbem. Phys. Letters 13 (1972) 89. [16] AL. ShGn, W-T. Chtig and hf_ Sbamoff, Chem- PhysLetters 15 (1972) 2136~ 1171 A-L. Shaln and hf_ Sharnoff, Chem_ Phys. Letters 16 (1972) 503. [18l A-L. Shah and hf. Shamoff, Chem_ Phys. Letters 22 (1973) 56_ [191 T-H. Cheng and N_ Hirota, J_ Chem. Phys. 56 (1972) 5019. [2OI J. Schmidt, WS- Veeman and J-H_ van der Waak, Chem. Phys. Letters 4 (1969) 341_ &?I 1 S. Niizuma and N- Hirota, J. Phys- Chem. 82 (1978) 453. f22] HE. Howard-Lock and G-W_ King. -~ J_ MoL Spectry. 36 (1970) 53. I231 J-W- Sidman, J. Cbem Phys. 29 (1958) 644_ 1241 R.L. ElIis. R_ Squire and H_H_ Jaffe. J_ Chem. Phvs- 5.5 _ (1971) 3499. I251 G-L- Bendazzoli and P. PaImieri, Intern. J. Quantum Chem. 8 (1974) 941. 1261 J-M- Robertson, Proc_ Roy. Sot A141 (1933) 594. 1271 E-W- Bim, R-Y- Dong nnd D.A. Ramsay, Chem. Phys.
Letters 18 <1973>11_