The crystal-field energy levels of some bis(ethylenediamine)copper(II) complexes
Abstract
The polarised single-crystal electronic spectra and e.s.r. spectra of six bis(ethylenediamine)copper(II) complexes have been interpreted in terms of a crystal field of D2h symmetry. The equatorial x- and y-co-ordinate axes were found to lie close to the copper–ligand bonds rather than between them, giving rise to a dx2–y2 ground state. In the Cu en2X2 complexes the sequence of one-electron energy levels is dx2–y2 > dz2 > dxzdyz with the position of the dxy orbital less certain, but probably lying between the dz2 and dxz,dyz levels. From the single-crystal e.s.r. spectra and the electronic energy levels the orbital reduction factors k⊥ and k∥ have been determined, and interpreted as molecular orbital coefficients.