Preparation and Structure of µ-Oxalato-bis{µ-oxo-µ-sulfido-bis[(oxalato)oxomolybdate(V)]} Complex, K6[{Mo2O3S(ox)2}2(ox)]·10H2O

The µ-oxo-µ-sulfido-(oxalato)molybdate(V) complex has been prepared and characterized by X-ray analysis. The potassium salt crystallizes in monoclinic system, space group C2/c, with cell dimensions a=13.640(3), b=20.296(3), c=15.213(4) Å, ß=106.42(2)°, and Z=4. The structure was solved by the heavy-atom technique and refined by the block-diagonal least-squares method to R=0.048 for 3552 independent reflections. The complex anion is tetrameric, two dimeric Mo2O3S(ox)2moieties being bridged by one oxalato ligand. Both the molybdenum atoms in the dimer are bridged by one sulfur and one oxygen atoms. Each molybdenum atom has distorted octahedral environment; two oxygen atoms of a bidentate oxalato ligand, bridging sulfur and oxygen atoms in the equatorial plane, a terminal oxygen and one of the bridging quadridentate oxalato ligand oxygens. The complex can be denoted as K6[{Mo2O3S(ox)2}2(ox)]·10H2O and has an approximate C2hsymmetry, with a crystallographic center of symmetry. The Mo–O (quadridentate bridging oxalato) bonds (2.304(4), 2.302(4) Å) are evidently longer than the Mo–O (bidentate oxalato) bonds (2.112(4), 2.102(4), 2.093(4), 2.120(4) Å). The influence of the bridging oxalato ligand on the geometry of Mo2O3S core will be discussed.