Hexahydro-closo-hexaborate as a ligand in coordination compounds: A secondpolymorph of [Au-2(mu-bis-eta(3)-B6H6)(PPh3)(2)]

The crystal structure of a second room-temperature polymorph of the complex [Au-2(mu-bis-eta(3)-B6H6)(PPh3)(2)] is presented and compared with the pre viously reported phase. The change of the solvent which is layered on a sol ution of [Au-2(mu-bis-eta(3)-B6H6)(PPh3)(2)] in CH2Cl2 from petroleum ether to n-pentane leads to a second form with fundamental differences in the cr ystal structure. Instead of the octahedrally shaped crystals, space group P a (3) over bar, the crystals in the present determination are orthorhombic needles crystallizing in space group Peen with a remarkable increased calcu lated density from 1.326 to 1.855 Mg/m(3).