Paramagnetic anisotropy and electronic structure of copper(II) tetraphenylporphin

Abstract

Magnetic anisotropy measurements have been made on copper(II) tetraphenylporphin over the temperature range 300-100 K. The sign of the anisotropy is consistent with the unpaired electron being in a d_xy orbital (where the x and y directions are between the adjacent nitrogen donor atoms). The temperature dependence of the principal molecular susceptibilities can only be explained by assuming a large second-order Zeeman term. The ligand-field parameters deduced from the present measurements are different from those obtained by e.s.r. studies, and reasons for these differences are discussed. The general application of magnetic anisotropy measurements to planar copper chelates is critically evaluated.