Theoretical study of the exchange coupling in copper(II) binuclear compounds with oxamidate and related polyatomic bridging ligands

A theoretical density functional study of the exchange coupling has been carried out for binuclear copper(II) compounds with oxamidate and related bridging ligands: oxalate, oxamate, ethylenetetraamidate, dithiooxamidate, dithiooxalate, tetrathiooxalate, bipyrimidine and bisimidazole. Model calculations have been used to examine the influence of the donor atoms at the bridging ligand and of the ligands' orientation on the coupling constant. Estimates for the singlet-triplet gap of complete structures of cis- and tians-oxamidato-bridged complexes are reported. Comparison of these results with those obtained from qualitative models provides some insight into the limits of applicability of these methods for the study of magnetostructural correlations.