Ligand-field splittings in noncubic complexes. Part VII. Calcium copper(II) acetate hexahydrate

Abstract

An angular overlap treatment with electrostatic corrections is applied to the d-orbital splitting in calcium copper(II) acetate hexahydrate CaCu(AcO)₄,6H₂O. All parameters used in the calculations are taken from previous results for tetragonal copper(II)–oxygen system. The relative energies of the d orbitals are predicted to be d_xy > d_x²-y² > d_z² > d_xz,yz and the calculated d–d transition energies are in excellent agreement with the observed spectrum. The effects of spin–orbit coupling and the binding of the distant oxygen ligands are discussed. It is concluded that these four distant atoms make relatively little contribution to the d-orbital splitting and their binding to the metal is largely electrostatic. The distortion of the four short-bonded oxygen atoms from square coplanarity also has a small effect on the d-orbital energies.