Three new pseudohalide bridged dinuclear Zn(II) Schiff base complexes: Synthesis, crystal structures and fluorescence studies

Three new dinuclear Zn(II) complexes [Zn(L)(mu(1,1)-N-3)Zn(L)(N-3)] center dot 1.5H(2)O (1), [Zn(L)(mu(1,1)-NCO)Zn(L)(NCO)] center dot 1.5H(2)O (2) and [Zn(L)(mu(1,1)-NCS)Zn(L)(NCS)(OH2)] (3) have been synthesized from a potentially tetradentate N2O2-donor Schiff base ligand LH, [LH = (OCH3)(OH)C6H3CHN(CH2)(2)N(CH3)(2)], which is the condensation product of o-vanillin and 2-dimethylaminoethylamine. All the three complexes 1, 2 and 3 have been characterized by elemental analysis, IR and H-1 NMR spectroscopy, TGA and fluorescence studies. Finally, their structures have been established by the single crystal X-ray diffraction method. Structural studies reveal that in complexes 1, 2 and 3 the two Zn(II) centers are held together by a mu(2)-phenolato oxygen atom and also by an end-on pseudohalide nitrogen (azide for 1; cyanate for 2; thiocyanate for 3) atom. Among the two deprotonated Schiff base ligands present in each complex, one acts as a tetradentate ligand (N2O2 donor set) while the other acts as a tridentate ligand (N2O donor set), having a non-coordinated methoxy group. All the synthesized complexes display intraligand (1)(pi-pi*) fluorescence and can potentially serve as photoactive materials. (C) 2007 Elsevier Ltd. All rights reserved.