Preferential azido bridging regulating the structural aspects in cobalt(III) and copper(II)-Schiff base complexes: Syntheses, magnetostructural correlations and catalytic studies

A tridentate NNO donor Schiff base ligand [(1Z,3E)-3-((pyridin-2-yl)methylimino)-1-phenylbut-1-en-1-ol = LH] in presence of azide ions coordinates with cobalt(II) and copper(II) ions giving rise to three new coordination complexes [Co-2(L)(2)(mu(1,1)-N-3)(2)(N-3)(2)] (1), [Cu-2(L)(2)(mu(1,3)-N-3)]center dot ClO4 (2) and [(mu(1,1)-N-3)(2)Cu-5(mu-OL)(2)(mu(1,1)-N-3)(4)(mu(1,1,1)-N-3)(2)](n) (3). The complexes have been characterized by elemental analysis, FT-IR, UV-Vis spectral studies, and single crystal X-ray diffraction studies. These complexes demonstrate that under different synthetic conditions the azide ions and the Schiff base ligand (LH) show different coordination modes with cobalt(II) and copper(II) ions, giving rise to unusual dinuclear and polynuclear species (1, 2 and 3) whose structural variations are discussed. Magneto-structural correlation for the very rare singly mu(1,3)-N-3 bridged Cu-II-Schiff base dinuclear species (2) has been studied. In addition, the catalytic properties of 1 for alkene oxidation and the general catalase-like activity behavior of 2 have been discussed. (C) 2011 Elsevier B.V. All rights reserved.