Synthesis and spectroscopic and structural investigation on tetrakis(N-(2-ammonioethyl)- piperazinium)di-mu-chloro-dodecachlorocuprate(II) bis(tetrachlorocuprate(II)), (C6H18 N3) Cu5Cl22

A red compound of the type [N(2amet)pipzH3]4Cu5Cl22 (N(2amet)pipzH3 = N-(2-ammonioethyl)piperazinium cation) was prepared and investigated by means of X-ray structural analysis, magnetic moment, and electronic and infrared spectroscopy. The substance crystallizes with four formula units in space group Ibam of the orthorhombic system in a cell of dimensions a = 16.697 (5) Å, b = 14.479 (3) Å, c = 23.757 (7) Å, and V = 5743.4 Å3 at 21°C. X-ray diffraction data were collected with a Philips PW 1100 automatic four-circle diffractometer, using Mo K? radiation. The structure was solved by direct methods; least-squares refinement of structural parameters led to a conventional R factor of 0.032 for 1246 independent reflections [I > 3.0?(I)]. The unit cell contains a Cu3Cl14 8- anion found for the first time, two unequally flattened CuCl4 2- tetrahedra, and [N(2amet)pipzH3]3+ trications, which are hydrogen bonded to anions. The central Cu atom of the centrosymmetric Cu3Cl14 8- ion has a tetragonally elongated octahedral six coordination, while the terminal Cu atoms have a distorted square-pyramidal pentacoordination; the coordination polyhedra share their axial Cl atoms. The contribution of hydrogen bonding to coordination geometry about the copper atoms is discussed. Its magnetic moment and electronic and infrared spectra are also interpreted on the basis of the known crystal structure.