Ab initio calculation on oxamidato-bridged binuclear copper(II) complex as structural unit

The investigation of the cis-trans conformations and their singlet and triplet electronic configurations of the oxamidato-bridged binuclear copper(II) complex unit Cu-2(oxen) (OH)(2) [H(2)oxen = N, N'-bis(2-aminoethyl) oxamide] has been carried out from ab initio calculation by using Gaussian 94W package and taking LanL2DZ basis set. The stabilities of the cis-trans conformations and the S-T configurations of the structural unit were discussed. It is indicated from the calculations that the triplet electronic configuration of the complex unit in trans-conformation is more stable. The reasons were analysed from the characteristics of its electronic structure, e.g., the population regularities of the charges and the compositions of the molecular orbitals. The results are in agreement with experimental regularities satisfactorily.