On the magnetic properties of some distorted octahedral high-spin iron(II) complexes

Abstract

A series of compounds, Fe(isoquinoline)₄X₂, Fe(pyridine)₄X₂, and Fe(phenanthroline)₂X₂, (X = Cl, Br, or l) and Fe(phenanthroline)₂(N₃)₂ were prepared and their magnetic susceptibilities were measured at temperatures in the range 20–300 K. The observed temperature dependence of the magnetic moment was used to evaluate the magnitude of the orbital reduction factor k, the low symmetry distortion parameter, Δ, and the extent of the reduction in spin–orbit coupling. The temperature dependence of the experimental magnetic moments for the isoquinoline and pyridine complexes was found to be in agreement with the theoretically predicted dependence for a complex with D_4h symmetry. In all of these compounds, except Fe(isoquinoline)₄l₂, the results indicate an orbitally nondegenerate (⁵B_2g) ground state. The same successful agreement was not found for all of the lower symmetry phenanthroline complexes. The derived crystal-field parameters are discussed and related to the structural properties of the complexes.