Heterometallic inorganic-organic frameworks of sodium-nickel(vanen): Cation-π interaction, trigonal dodecahedral Na+ and unprecedented heptadentate coordination mode of vanen2-

Three heterometallic nickel(II)-sodium(I) complexes, [Ni(vanen)Na(NO3)] (1), [Ni(vanen)Na(vanen)Ni] BF4 (2) and [Ni(vanen)Na(ClO4)](n) (3), have been synthesized by reacting nickel(II) and H-2 vanen with sodium(I), varying the reaction conditions and stoichiometry of the reactants [H(2)vanen = N,N'-ethylene-bis(3-methoxysalicylideneimine)]. All the three complexes have been characterized by X-ray single-crystal diffraction studies. In all the three complexes, nickel(II) is placed in the N2O2 environment and sodium(I) is placed in the O-4 compartment of the compartmental Schiff base. In each complex, nickel(II) is square planar. Sodium(I) is trigonal dodecahedral in complex 2, and pentagonal pyramidal both in complexes 1 and 3. The nitrate ion is coordinated to sodium(I) in a chelating bidentate fashion. The sodium(I) in complex 1 shows strong pi interaction with the phenyl ring of a second molecule. In complex 3, a carbon atom from an aryl group of a symmetry-related molecule is connected with sodium(I) in eta(1) fashion to constitute 1D chain. The structure of complex 3 reveals an unprecedented heptadentate coordination mode of the deprotonated Schiff base. (C) 2013 Elsevier Ltd. All rights reserved.