Single-crystal electronic and electron spin resonance spectra of bis-(diethylenetriamine)copper(II) nitrate

Abstract

The polarised single-crystal electronic spectra and e.s.r. spectrum of Cu(dien)2(NO3)2 are interpreted in C2 effective symmetry, with a dz2 ground-state. This yields the one-electron orbital sequence dz2 > dx2–y2, dxy > dxz, dyz; the precise order of the dx2–y2 and dxy levels is not certain, but that with the dx2–y2 above the dxy level is preferred. The low energy of the dx2–y2→dz2 transition reflects the small ‘ tetragonal ’ distortion arising from the out-of-plane chelation of diethylenetriamine. A method is given for calculating the molecular g-values, for rhombic symmetry, from data on crystals containing four inequivalent orientations.