Bis-(bis-(1,3-diaminopropane)-copper(II) tetracyanonickellate(II)) tetrahydrate:: Preparation, characterization, and crystal structure of a novel molecular tetracyanonickellate

[Cu(tn)(2)Ni(CN)(4)](2) . 4H(2)O and Cu(tn)(2)Ni(CN)(4) (tn = 1,3- diaminopropane) were prepared and characterized. The hydrate is unstable on air and readily dehydrates to Cu(tn)(2)Ni(CN)(4). Crystal structure analysis of the hydrate at 150 K revealed a novel tetranuclear molecular structure of the tetracyanonickellate. The building elements are two[Cu(tn)(2)](2+) cations (coordination numbers of Cu: 5 and 6, respectively), two [Ni(CN)(4)](2-) anions, and crystal water. The two cations are linked by one tetracyanonickellate anion via bridging cyano groups placed in cis positions. The second anion is bound weakly (Cu-N = 2.82 Angstrom) via one mu (2)-bridging cyano ligand. The tetranuclear molecules and pairs of solvate water molecules are linked by strong hydrogen bonds, thus forming infinite planes which an linked in the third dimension by considerably weaker hydrogen bonds.