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Y. Niwa, D. R. Lloyd, and H. Kobayashi
[J. Electron Spectrosc. Relat. Phenom., Vol. 66, p. 55, 1993]
He I and He II photoelectron spectra of tricarbonylchromium-complexed benzene derivatives are reported and assigned. Comparisons with the free arenes suggest that in all the cases studied, the spectra can be interpreted in terms of charge donation from the ring to the Cr(CO)_{3} group as a whole: electronic effects at Cr are also visible at the C and O atoms as shifts in ionization energy. Ionization energies for orbitals localized mainly on the substituents also shift, to an extent which depends on the "conjugation" between ring and substituent; conjugation in the complexes appears to be similar to that in the free arenes. The shifts in ionization energy observed for chlorobenzene chromium tricarbonyl are shown as an example. Correlations of the observations with those in bis-arene complexes, and in surface-coordinated arenes, are discussed.
