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- diaminop ropane) were prepared and characterized. The hydrate is unstable on air and readily dehydrates to Cu(tn)(2)Ni(CN)(4). Crystal structure analysis of th e 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-) a nions, and crystal water. The two cations are linked by one tetracyanonicke llate anion via bridging cyano groups placed in cis positions. The second a nion is bound weakly (Cu-N = 2.82 Angstrom) via one mu (2)-bridging cyano l igand. The tetranuclear molecules and pairs of solvate water molecules are linked by strong hydrogen bonds, thus forming infinite planes which an link ed in the third dimension by considerably weaker hydrogen bonds.