Crystal structure characterization of a polynuclear complex between copper(II), tris(2-aminoethyl)amine and ferrocyanide

The addition of [Fe(CN)(6)](4-) to [Cu(tren)](2+) [tren = tris(2-aminoethyl)amine] gives a polynuclear complex of formula [(tren)Cu(NC)Fe(CN)(4)(CN)Cu(tren)]. 12(H)O, which has been characterized by spectroscopic techniques and single crystal X-ray analysis. The asymmetric unit comprises half a molecule and the iron atom is at the centre of symmetry. The [Cu(tren)](2+) and [Fe(CN)(6)](4-) ions are linked together through cyanide bridges. Of the six CN- groups around the iron atom, four are not bonded to copper atoms, but only interact through hydrogen bonds with the water molecules present in the lattice, the remaining two coordinate to copper atoms of adjacent [Cu(tren)](2+) moieties, leading to a non-linear Fe-C=N-Cu chain. The presence of six water molecules per asymmetric unit of the complex gives rise to an extensive hydrogen-bonded system. Infrared and electronic spectral results are discussed and related to the crystal structure. Copyright (C) 1996 Elsevier Science Ltd