Use of multi-N-donor ligands for preparation of organic–inorganic hybrid materials: Crystal structures of ionic [M(aepn)2][Ni(CN)4]·H2O and polymeric M(aepn)Ni(CN)4 (M = Zn(II), Cd(II); aepn = N-(2-aminoethyl)-1,3-propanediamine)

From aqueous systems M-aepn-[Ni(CN)4]2− (M = Zn, Cd; aepn = [N-(2-aminoethyl)-1,3-propanediamine]) using variable M: aepn molar ratios [Cd(aepn)2] [Ni(CN)4]·H2O (1), Cd(aepn)Ni(CN)4 (2), [Zn(aepn)2][Ni(CN)4]·H2O (3) and Zn(aepn)Ni(CN)4 (4) have been prepared and identified. Single crystal X-ray structure analyses have shown that the crystal structures of 1 and 3 are ionic and are built up of [Zn(aepn)2]2+ and [Cd(aepn)2]2+ cations, respectively, [Ni(CN)4]2− anions and water molecules of crystallisation, and 2 and 4 exhibit polymeric structures. In the three-dimensional structure of 2 two crystallographically independent tetracyanonickellate anions are placed on inversion centres and exhibit connectivities two and four, respectively, with bridging cyano groups linking cadmium and nickel atoms. Octahedrally coordinated cadmium atom exhibits connectivity three. In one-dimensional structure of 4 [Ni(CN)4]2− anions and [Zn(aepn)]2+ cations are linked via bridging cyano ligands. Both building species exhibits connectivity two. One chelate bonded aepn ligand blocks three coordination sites on the penta-coordinated Zn(II) atom.