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. Vibronic sources of parity mixing, providing the whole contribution to intensity in the centric, planar species but a much smaller contribution in the ''tetrahedral'' species are included for bending vibrations only. Contributions from different bending modes and, as appropriate, from the static field are all related after normal coordinate analysis of vibrational frequencies to four underlying ''static'' CLF intensity parameters (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 essentially unique parameter sets. Chemically sensible variations in the parameter values are observed with respect to both geometry and d(n) configuration. Comparisons of intensity parametrizations are made here with respect to the larger group of closely related chromophores analyzed by the CLF model to date.