First report of singly phenoxo-bridged copper(II) dimeric complexes: synthesis, crystal structure and low-temperature magnetic behaviour study

Three singly phenoxo-bridged dinuclear Cu(II) complexes [Cu-2(L)(2)(SCN)(H2O)](ClO4) 1, [Cu-2(L)(2)(N-3)(H2O)](ClO4) 2, [Cu-2(L)(2)(NCO)(H2O)](ClO4) 3 (HL is the Schiff base ligand derived from O-vanillin and 2-aminomethyl ethylenediamine) have been synthesised and characterised by infrared, UV-Vis spectra, electrochemical study and single crystal X-ray diffraction study. In all the complexes (1-3), there are two geometrically different square pyramidal copper(II) centres, with N3O2 and N2O3 donor sets for the two Cu(II) centres. In the dimeric unit, the copper atoms are held together by only one distinct rare mu(2)-phenolate oxygen of one Schiff base. The Cu-Cu distances are 3.291(2), 3.244(1) and 3.244(1) Angstrom for complexes 1, 2 and 3, respectively, and the Cu-O-Cu angles are found to be 111.5(1), 109.3(2), 109.6(1)degrees for complexes 1, 2 and 3, respectively. Variable temperature magnetic susceptibility study on the complexes 1,2 and 3 indicate the presence of antiferromagnetic coupling between the Cu(II) centres with 2J values -109.8, -103.9 and -95.9 cm(-1), respectively.