Ligand field splittings in non-cubic complexes. Part I. Tetragonal copper(II)—nitrogen systems

Abstract

The relative energies of the d-orbitals in tetragonal copper(II) complexes with ammonia and ethylenediamine are discussed in terms of a simple empirical theory. The d-orbital splitting is considered to arise from both σ-antibonding and electrostatic effects. The former is calculated from angular overlap considerations and the latter by applying the perturbation of point charges placed at the ligand atoms. The three d–d bands in Cu(NH₃)₄²⁺ and Cu en₂²⁺ can be satisfactorily fitted to two freely chosen parameters, and the ‘pentammine effect’ in the ammine adducts of these is explained.