Structure and magnetic properties of a tetranuclear Cu4O4 open-cubane in [Cu(L)]4•4H2O with L2- = (E)-N′-(2-oxy-3-methoxybenzylidene)benzohydrazide

The in-situ formed hydrazone Schiff base ligand (E)-N'-(2-oxy-3-methoxybenzylidene) benzohydrazide (L-2) reacts with copper(II) acetate to a tetranuclear open cubane [Cu(L)](4) complex which crystallizes as two symmetry-independent (Z' = 2) S-4-symmetrical molecules in different twofold special positions with a homodromic water tetramer. The two independent (A and B) open- or pseudo-cubanes with Cu4O4 cores of 4 + 2 class (Ruiz classi. cation) each have three different magnetic exchange pathways leading to an overall antiferromagnetic coupling with J(1B) = J(2B) = -17.2 cm (1) , J(1A) = -36.7 cm (1), J(2A) = -159 cm (1), J(3A) = J(3B) = 33.5 cm (1), g = 2.40 and rho = 0.0687. The magnetic properties have been analysed using the H = -Sigma(i,j)J(ij)(SiSj) spin Hamiltonian. (C) 2009 Elsevier B.V. All rights reserved.