The magnetic behaviour of cubic-field 4T1g terms in lower symmetry

Abstract

The behaviour of the magnetic properties of the ⁴T_1g term under simultaneous perturbation by spin–orbit coupling and an axial ligand-field is presented. The theory is applied to the variation with temperature of fifteen octahedral cobalt(II) complexes in the range 80–300°K. The values of k, the orbital reduction factor, deduced for the present complexes are determined mainly by the absolute magnitudes of the mean susceptibilities, while those of the axial-field splitting, Δ, and spin–orbit coupling coefficient are determined more by the temperature variation of the moments. It is found that for these compounds, where the variation of the magnetic moment with temperature is not large, there is usually uncertainty concerning the magnitude, and even the sign, of Δ.