X.alpha.-SW calculations of the electronic structure and magnetic properties of weakly coupled transition-metal clusters. The [Cu2Cl6]2- dimers

The self consistent field multiple scattering Xa model has been used to calculate the electronic structure and the magnetic coupling constant, J , of planar and pseudotetrahedral [ C U ~ C I ~co]m~p-l exes with the aim of exploiting the actual possibilities of the model to describe the spectral (electronic and EPR) and magnetic properties of transition-metal polynuclear complexes. The observed variation of J with the degree of tetrahedral distortion has been quantitatively reproduced. The 19 000-cm-' feature characteristic of the electronic spectra of hexachlorodicuprate(l1) complexes is computed in the present calculations as a chlorine-to-metal charge transfer