DYNAMIC LIGAND-FIELD THEORY FOR SQUARE-PLANAR TRANSITION-METAL COMPLEXES

The electron-phonon coupling of square planar transition metal complex es is analysed by a perturbative model based on the electrostatic liga nd-field theory. Excited-state potential energy surfaces are character ized by taking into account linear vibronic coupling within the point group D-4h. Results do not depend on new adjustable parameters and can be generalized to a great number of complexes. The applicability of t he model is demonstrated by comparing the results of the model with th ose obtained from the optical spectra of [CuCl4](2-) and [MX4](2-) (wh ere M = Pd, Pt and X = Cl, Br). In particular, the influence of E x (b (1g) + b(2g)) coupling, which is the subject of some controversy in th e literature, is found to be of low importance. (C) 1998 Elsevier Scie nce B.V.