EFFECT OF CRYSTAL-FIELD ON THE SPIN-DENSITY AT THE COPPER NUCLEUS IN COPPER-COMPLEXES

The role of lower symmetry component of the crystal field in causing a mixing of excited 3d(x-1)4s with the ground 3d(x) configuration and l eading to spin density at the nucleus for iron group ions was suggeste d by Griffith and Orgel. This mechanism has been examined in detail fo r the two tow-symmetry copper complexes, one square planar (D-4h symme try) and the other distorted tetrahedron (D-2d symmetry) and the calcu lation has been performed using the powerful Racah method and tenser o perator technique. It is found that for the two types of copper comple xes, copper pthalocyanin (square planar, D-4h symmetry) and cesium cop per chloride (distorted tetrahedron, D-2d symmetry) the contribution f rom this mechanism to the spin density at the nucleus vanishes identic ally.