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

Abstract

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 H2 vanen with sodium(I), varying the reaction conditions and stoichiometry of the reactants [H2vanen=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 O4 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 π 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 η1 fashion to constitute 1D chain. The structure of complex 3 reveals an unprecedented heptadentate coordination mode of the deprotonated Schiff base.