OXALATO-BRIDGED AND RELATED DINUCLEAR COPPER(II) COMPLEXES - THEORETICAL-ANALYSIS OF THEIR STRUCTURES AND MAGNETIC COUPLING

A theoretical analysis of the structural variations found for dinuclear Cu(II) complexes with oxalato and related polynuclear bridging ligands and their influence on the magnitude of the magnetic exchange interactions is presented in this paper. The family of compounds studied can be represented by the general formula [(AA)CU(μ − C2O4)CU(AA)]XN, where AA can be a chelating ligand like 2,2 ′ -bipyridine (bpy) or tetramethylethylenediamine (tmen), and X is a counteranion or a solvent molecule. Three types of distortions from an ideal square-planar geometry around the copper atoms are considered: (1) the removal of the copper ions from the ligands′ plane; (2) a twist of the square planar A2CuO2cores toward a tetrahedral geometry by rotation of the AA ligand; (3) folding of the A2Cu-ox-CuA2skeleton through the O- -O hinges and axial coordination of X. An evaluation of second-order Jahn-Teller distortions through the analysis of orbital topologies and atomic electronegativities is presented, which might be helpful in predicting how stable a distorted molecule is relative to the undistorted one, as well as the relative extent for such distortions in a series of related structures. © 1990, American Chemical Society. All rights reserved.