Hexahydro-closo-hexaborate as a Ligand in Coordination Compounds: A Second Polymorph of [Au2(μ-bis-η3-B6H6)(PPh3)2]

Abstract

The crystal structure of a second room-temperature polymorph of the complex [Au2(μ-bis-η3-B6H6)(PPh3)2] is presented and compared with the previously reported phase. The change of the solvent which is layered on a solution of [Au2(μ-bis-η3-B6H6)(PPh3)2] in CH2CI2 from petroleum ether to n-pentane leads to a second form with fundamental differences in the crystal structure. Instead of the octahedrally shaped crystals, space group Pa3̄, the crystals in the present determination are orthorhombic needles crystallizing in space group Pccn with a remarkable increased calculated density from 1.326 to 1.855 Mg/m3.