Charge transfer spectra and structure of the copper (II) halide complexes

Abstract

An exhaustive critical literature survey has been made of the spectra reported for copper (II) halide complexes. When this is supplemented with data from this laboratory for dry and moist acetic acid solutions, there are available reasonably detailed spectral data for about 10 such complexes of differing stoichiometry and geometry. The d— d and charge transfer spectra of the various complexes can be fitted within 1500 cm −1 by a simple semi-empirical theory. σ-bonds and π-bonds are treated as perturbations on the copper d-orbitals, using a simple “point bond” model to allow for the effects of different geometry. These simple calculations are sufficiently accurate to permit definite conclusions from the spectra concerning the stoichiometry and geometry of copper halide species observed in solution. Thus the CuBr 3 − ion cannot be assigned D3 h symmetry.