Layered perovskite-related ruthenium oxychlorides:: crystal structure of two new compounds Ba5Ru2Cl2O9 and Ba6Ru3Cl2O12

Single crystals of the title compounds were prepared using a BaCl2 flux and investigated by X-ray diffraction methods using MoKalpha radiation and a charge coupled device (CCD) detector. The crystal structures of these two new compounds were solved and refined in the hexagonal symmetry with space group P6(3)/mmc, a = 5.851 (1) Angstrom, c = 25.009(5) Angstrom, rho(cat) 4.94 g cm(-3) Z = 2 to a final R-1 = 0.069 for 20 parameters with 312 reflections for Ba5Ru2Cl2O9 and space group P (3) over bar ml. a = 5.815(1) Angstrom, c = 14.915(3) Angstrom rho(cat) 5.28 g cm(-3), Z = 1 to a final R-1 = 0.039 for 24 parameters with 300 reflections for Ba6Ru3Cl2O12. The structure of Ba5Ru2Cl2O9 is formed by the periodic stacking along [001] of three hexagonal close-packed BaO3 layers separated by a double layer of composition Ba2Cl2. The BaO3 stacking creates binuclear face-sharing octahedra units Ru2O9 containing Ru(V). The structure of Ba6Ru3Cl2O12 is built up by the periodic stacking along [001] of four hexagonal close-packed BaO3 layers separated by a double layer ofcomposition Ba2Cl2. The ruthenium ions with a mean oxidation degree + 4.67 occupy the octahedral interstices formed by the four layers hexagonal perovskite slab and then constitute isolated trinuclear Ru3O12 units. These two new oxychlorides belong to the family of compounds formulated as [Ba2Cl2][Ba-n + 1RunO3n + 3] where n represents the thickness of the octahedral string in hexagonal perovskite slabs. (C) 2003 Elsevier Inc. All rights reserved.