Syntheses, Structures and Magnetic Properties of Ferromagnetically/Antiferromagnetically Coupled Penta- and Hexanuclear Azido-Bridged Nickel(II) Coordination Compounds

The use of the Schiff base ligand (HL) derived from 2,6-diformyl-4-methylphenol andN,N-dimethyldipropylenetriamine in nickel(II) coordination chemistry has been investigated and two pentanuclear [Ni-5(H2L)(2)(mu(1,1)-N-3)(4)(N-3)(2)(mu(3)-OH)(2)(H2O)(2)](NO3)(4)center dot 6H(2)O (1), [Ni-5(L)(2)(mu(1,3)-OAc)(2)(mu(1,1)-N-3)(4)(mu(3)-OH)(2)]center dot 12H(2)O center dot 2CH(3)OH (2) and one hexanuclear [Ni-6(H2L)(2)(mu(1,1)-N-3)(4)(mu(1,3)-N-3)(2)(N-3)(4)(mu(3)-OH)(2)(H2O)(2)](ClO4)(2)center dot 4H(2)O (3) clusters were isolated under mild conditions. In these complexes, the nature of the anion and stoichiometry of the reactants seem to play important roles in directing the formation of the metal clusters. Their X-ray characterization shows that the Ni(6)cluster can be considered to be built from two triangular [Ni-3(mu-phenoxido)(mu(3)-OH)(mu-N-3)(4)] subunits with bis(mu(1,3)-N-3) connectors, while bowtie-shaped Ni(5)clusters are formed by sharing a common vertex. Variable temperature magnetic properties of the penta- and the hexanuclear nickel(II) spin coupled clusters have been investigated and interpreted. According to the present results, although the core structures of triangular Ni(3)units are identical in these systems, the introduction of different bridges bring overall diverse magnetic interaction (antiferromagnetic to ferromagnetic) in these nickel(II) clusters.