Chelating Schiff base assisted azide-bridged Mn(II), Ni(II) and Cu(II) magnetic coordination polymers

Four new Mn(II), Ni(II) and Cu(II) coordination polymers [Mn-2(L-1)(mu(1,1)-N-3)(2)(mu(1,3)-N-3)(2)](n) (1), [Ni(L-2)(2)(mu(1,3)-N-3)](n)(ClO4)(n) (2), [Cu(L-3)(mu(1,1)-N-3)(N-3)](n) (3) and [Cu(L-4)(mu(1,1)-N-3)(2)](n) (4) (L-1 = N, N'-bis(2-pyridylmethylene)ethane-1,2-diamine, L-2 = N-(2-pyridylmethylene)methylamine, L-3 = N-(2-pyridylmethylene)-3-pyridylamine, L-4 = N-(2-pyridylmethylene)-tbutylamine) have been synthesized and characterized by single-crystal X-ray analysis and magnetic measurements. Complex 1 indicates a stoichiometry-dependent structural change (based on Mn : L-1 : N-3 = 2 : 1 : 4 molar ratio) and consists of two-dimensional (2-D) (4,4) net layers, in which Mn(II) centers are co-bridged by single end-to-end (EE), double end-on (EO) azide and chelate-bridging L-1 ligands. Complex 2 shows a single EE azide-bridged one-dimensional (1-D) Ni(II) chain. Complexes 3 and 4 indicate single EO and double EO azide-bridged 1-D Cu(II) chains, respectively. Complex 1 exhibits weak ferromagnetism due to its intra-layer spin-canting with T-c = 20 K. Complex 2 shows an unusual intra-chain ferromagnetic coupling and spin-canting behaviour. Both complexes 3 and 4 exhibit intra-chain antiferromagnetic interactions. Magneto-structural parameters for these related complexes were also discussed.