AN EFFECTIVELY DIAMAGNETIC OXIMATO-BRIDGED ASYMMETRIC DINUCLEAR COPPER(II) COMPLEX WITH A CU(II)-I BOND

A new bis(oximato)-bridged dinuclear copper(II) complex containing an axial Cu(II)-I bond with the formula [LCu(PyA)(2)Cu(I)]ClO4.CH3CN (1) (where L = 1,4,7-trimethyl-1,4,7-triazacyclononane; PyA = monoanion of pyridine-2-aldoxime) has been characterized by IR, UV-Vis, variable temperature (81-283 K) magnetic susceptibility measurements. 1 crystallizes in the monoclinic system space group P2(1)/n, with cell constants a = 8.304(2), b = 27.410(7), c = 13.975(5) Angstrom, beta = 93.48(2)degrees, V = 3175(2) Angstrom(3) and Z = 4. The structure consists of oximato-bridged (CuCuII)-Cu-II(I) monocations and non-coordinated perchlorate anions. Both copper ions have a distorted square-pyramidaI geometry with a Cu...Cu separation of 3.45 Angstrom and Cu(II)-I bond length of 2.74 Angstrom. The copper centres are very strongly antiferromagnetically coupled, the singlet-triplet splitting being greater than 1000 cm(-1).