Dinuclear and heptanuclear nickel(II) complexes: Anion coordination induced ligand arm hydrolysis and aggregation around a nickel(II) core

The heptanuclear and tetracationic nickel(II) complex [Ni-7(mu(3)-OH)(6)(mu(3)-H2L)(4)](NO3)(4)center dot 2MeOH (3.2MeOH); (H3L is 2,6-bis-[(3-hydroxy-propylimino)-methyl]-4-methyl-phenol), featuring four defective cubanes around a pivotal nickel(II) ion, has been obtained via hydroxido-bridge-induced assemblage of two Ni-3 fragments. Presence of azido (N-3(-)) and bromido (Br-) ions in reactions on the contrary lead to one ligand imine arm hydrolysis and formations of [Ni-2(N-3)(2)(mu-HL1)(2)(OH2)(2)] (1) and [Ni2Br2(mu-HL1)(2)(OH2)(2)] (2); where H(2)L1 is 2-hydroxy-3-[(3-hydroxy-propylimino)-methyl]-5-methyl-benzaldehyde. X-ray structural analyses of 3 show six symmetrically positioned Ni-II around a central Ni-II and bridged by six in situ generated hydroxido groups from solvent water molecules. Density functional theory (DFT) calculations have also been performed to predict magnetic behavior of the complexes. The spin density surface of compounds 1 and 2 has been also obtained. (C) 2013 Elsevier Ltd. All rights reserved.