A rare ferromagnetically coupled asymmetric doubly azido bridged copper(II) dimer with an N, N, O donor Schiff base

A new end-to-end (EE) doubly azido bridged dinuclear complex [Cu2L2(mu(1,3)-N-3)(2)] (1) [where L = (E)-4-(2-(dimethylamino)ethylimino)-1,1,1-trifluoropentan-2-one)] has been synthesized and characterized by elemental and spectroscopic techniques. Single crystal X-ray diffraction analysis reveals that the dimeric complex possesses a center of inversion. Each copper atom in 1 is in a distorted square pyramidal geometry with a CuN4O chromophore as revealed from the T value, 0.19. The four basal positions are occupied by two imine N and one keto O atom of the Schiff base and one N atom from the azide anion. Another N atom from a coordinated azide occupies the apical position. Temperature dependent magnetic susceptibility of 1 was fitted using the Bleaney-Bowers expression which led to the parameters J = 13.6 cm(-1) and R = 3.4 x 10(-5). It indicates a ferromagnetic interaction through the double azido bridges connecting the individual copper Schiff base units. (C) 2006 Elsevier Ltd. All rights reserved.