The electronic properties and stereochemistry of the copper(II) ion. Part V. The tetra-ammine complexes

Abstract

The polarised single-crystal electronic spectra and e.s.r. spectra of six tetra-amminecopper(II) complexes of known crystal structure have been examined. In the two tetragonal octahedral complexes the order of the one-electron orbital energy levels is established as d_x²–y² > d_z² > d_xy > d_xz,d_yz. In the strictly square coplanar complex Na₄ Cu(NH₃)₄[Cu(S₂O₃)₂], the order of the d_xy and d_xz,d_yz levels may be inverted. The energy of the d_z²â†�d_x²–y² transition can be used as a measure of the relative tetragonal distortion present and is correlated with the in-plane copper–nitrogen bond lengths. From the single-crystal e.s.r. spectra and the electronic energy levels the orbital reduction parameters are estimated.