STATIC AND VIBRONIC CONTRIBUTIONS TO THE SPECTRAL INTENSITIES OF TETRAHALOCOPPER(II), TETRAHALOPLATINUM(II), AND TETRAHALOPALLADIUM(II) CHROMOPHORES

The intensity distributions in the ligand-field spectra of nine planar and ''tetrahedral'' complexes [MCl(4)](2-) (M Pt, Pd, Cu; X = Cl, Br) have been modeled within a cellular ligand-field (CLF) approach. Vibr onic sources of parity mixing, providing the whole contribution to int ensity in the centric, planar species but a much smaller contribution in the ''tetrahedral'' species are included for bending vibrations onl y. Contributions from different bending modes and, as appropriate, fro m the static field are all related after normal coordinate analysis of vibrational frequencies to four underlying ''static'' CLF intensity p arameters (P)t(sigma), (F)t(sigma), (P)t(pi), and (F)t(pi). In fitting intensity distributions, only three of these are free variables. All intensity analyses proceeded successfully and briskly to define essent ially unique parameter sets. Chemically sensible variations in the par ameter values are observed with respect to both geometry and d(n) conf iguration. Comparisons of intensity parametrizations are made here wit h respect to the larger group of closely related chromophores analyzed by the CLF model to date.