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Aromatic Carbonyl Spectra. I. The Polarized Absorption Spectrum of Single‐Crystal 4,4′‐Dichlorobenzophenone
1.(a) S. F. Mason, Quart. Rev. 17, 20 (1963);
1.(b) Optical Rotatory Dispersion and Circular Dichroism in Organic Chemistry, G. Snatzke, Ed. (Heyden and Son, 1967).
2.Organic Photochemistry, O. L. Chapman, Ed. (Marcel Dekker, New York, 1967).
3.J. W. Sidman, Chem. Rev. 58, 689 (1958).
4.M. Kasha, Discussions Faraday Soc. 9, 14 (1950).
5.G. H. Dieke and G. B. Kistiakowsky, Phys. Rev. 45, 4 (1934).
6.J. C. D. Brand, J. Chem. Soc. 1956, 858.
7.G. W. Robinson, Can. J. Phys. 34, 699 (1956).
8.J. H. Callomon and K. K. Innes, J. Mol. Spectry. 10, 166 (1963).
9.D. E. Freeman and W. Klemperer, J. Chem. Phys. 45, 52 (1966).
10.J. A. Pople and J. Sidman, J. Chem. Phys. 27, 1270 (1957).
11.J. Prochorow, A. Tramer, and K. L. Wierzchowski, J. Mol. Spectry. 19, 45 (1966).
12.(a) J. C. D. Brand, J. G. Callomon, and J. K. G. Watson, Discussions Faraday Soc. 35, 175 (1963);
12.(b) J. C. D. Brand and G. D. Williamson, Discussions Faraday Soc. 35, 184 (1963)., Discuss. Faraday Soc.
13.R. C. Cookson and N. S. Wariyar, J. Chem. Soc. 1956, 2302.
14.H. Labhart and G. Wagniere, Helv. Chim. Acta 42, 2219 (1959).
15.(a) S. F. Mason, J. Chem. Soc. 1959, 1240;
15.(b) J. M. Hollas, Spectrochim. Acta 20, 1563 (1964);
15.(c) J. A. Merritt and K. K. Innes, Spectrochim. Acta 14, 945 (1960);
15.(d) K. K. Innes and L. E. Giddings, Jr., Discussions Faraday Soc. 35, 192 (1963).
16.V. G. Krishna and L. Goodman, J. Chem. Phys. 36, 2217 (1962).
17.R. Shimada and L. Goodman, J. Chem. Phys. 43, 2027 (1965).
18.D. S. McClure and P. L. Hanst, J. Chem. Phys. 23, 1772 (1955).
19.C. Dijkgraf and J. P. G. Rousseau, Spectrochim. Acta A23, 1681 (1967). During the course of this work, this report on the polarized absorption spectrum of 4,‐dichlorobenzophenone at room temperature appeared. Only the progression of broad bands belonging to the Carbonyl stretching mode was observed.
20.J. Tanaka and M. Shibata, Bull. Chem. Soc. Japan 41, 34 (1968).
21.M. Vala and J. Tanaka, J. Mol. Spectry. (to be published).
22.J. Toussaint, Ph.D. thesis, University of Liege, 1952.
23.J. R. Platt, J. Chem. Phys. 19, 101 (1951).
24.The transition may be observed by several other mechanisms such as magnetic dipole, electric quadrupole, or rotational‐electronic interaction, but these are generally less important intensitywise.
25.G. Wagniere, J. Am. Chem. Soc. 88, 3937 (1966).
26.A. Moscowitz, Advan. Chem. Phys. 4, 67 (1962).
27.J. A. Schellman and P. Oriel, J. Chem. Phys. 37, 2114 (1962).
28.The transition in the Carbonyl group is magnetic dipole allowed, but is expected to be about to times as intense as the strong electric‐dipole‐allowed transitions in the ultraviolet. Generally speaking, magnetic dipole transitions are rarely observed in polyatomic molecules.29 Nevertheless, a magnetic dipole transition has been observed for the 0‐0 band in the transition of formaldehyde. It is interesting to examine the polarization properties for an allowed magnetic dipole transition. A z‐polarized magnetic dipole transition such as for will be observed in a crystal with electric polarization in the x, y molecular plane, i.e., perpendicular to the Carbonyl axis. At first sight, this conclusion appears at variance with the result of Callomon and Innes8 on formaldehyde, who found the rotational structure of the 0‐0 and related Vibronic transition to be polarized parallel to the Carbonyl axis. But as Herzberg30 points out, the rotational structure of a magnetic dipole transition is entirely similar to that of an ordinary allowed electric dipole transition because the selection rules for rovibronic species change whereas the J and K selection rules remain the same. Therefore, there is no inconsistency in the two conclusions.
29.G. Herzberg, Electronic Spectra of Polyatomic Molecules (D. Van Nostrand Co., Inc., Princeton, N.J., 1966) p. 134.
30.Reference 29, p. 270.
31.H. C. Longuet‐Higgins, Mol. Phys. 6, 445 (1963).
32.H. D. Bist, J. C. D. Brand, and D. R. Williams, J. Mol. Spectry. 21, 76 (1966).
33.S. Nagakura and J. Tanaka, J. Chem. Phys. 22, 236 (1954).
34.The spin‐forbidden transition was, however, observed at M. Vala and J. Tanaka (to be published).
35.A crystal‐induced 0‐0 transition is highly unlikely in the present case. Since the site and molecular symmetry are the same it is expected that molecular effects will be overwhelmingly important compared to site perturbations.
36.F. A. Miller, W. G. Fateley, and R. E. Witkowski, Spectrochim. Acta A23, 891 (1967).
37.W. A. Fateley, R. K. Harris, F. A. Miller, and R. E. Witkowski, Spectrochim. Acta 21, 231 (1965).
38.In a phosphorescence study of crystalline DCBP, we have observed several regularly repeated frequency intervals of which may involve transitions to ground‐state torsional levels. M. Vala and J. Tanaka (to be published).
39.Professor W. B. Person has suggested that the intensity alternation may also be the result of the Franck‐Condon principle operating between the two electronic states both of which contain a double minimum.
40.W. D. Chandler and L. Goodman, J. Chem. Phys. 45, 4088 (1966).
41.A. C. Albrecht, J. Chem. Phys. 33, 156 (1960).
42.Actually two types of intramolecular CT transitions are possible: a phenyl π to Carbonyl orbital transition and a Carbonyl n orbital to phenyl orbital transition. Labhart and Wagniere14 have theoretically examined these alternatives for transitions in β, γ unsaturated ketones and found that although the orbital overlap in the latter mechanism is larger, the energy of the former transition is more favorable. Consequently, it was concluded that the phenyl π‐to‐carbonyl CT transition is the most likely source of intensity gain in these compounds.
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