Determination of solution structures of binuclear copper(II) complexes

Abstract

A simple and efficient method for the determination of solution structures of weakly coupled binuclear copper(II) complexes is described. The technique involves the combination of molecular mechanics and EPR spectroscopy and has been applied to the binuclear copper(II) complexes of 5,5'-bis(3,7-dehydro-3,7-diazanonane-4,6-dione-1,9-diamine) (L1), 5,5'-bis(3,7-diazanonane-1,9-diamine) (L2), and 5-methyl-5-nitro-3,7-diazanonanedioate (L3). The complexes [Cu2L1].10H2O and [Cu2L2](ClO4)4 were also characterized by X-ray crystallography. (Cu2L1].10H2O: space group P1BAR; a = 7.669 (2), b = 8.757 (3), c = 10.596 (2) angstrom; alpha = 79.57 (3), beta = 83.36 (2), gamma = 89.17 (3)-degrees. [Cu2L2] (ClO4)4: space group P3(2)21; a = 13.671 (2), b = 13.671 (2), c = 13.929 (2) angstrom. There is excellent agreement between the X-ray crystal structures and the structures predicted by molecular mechanics and EPR spectroscopy, Electrochemical properties of the binuclear complexes are also reported.