SYNTHESIS, CHARACTERIZATION AND BONDING OF FULVALENE DIMOLYBDENUM(III) AND DITUNGSTEN(III) CATIONS WITH ONE THIOLATE BRIDGING LIGAND - CRYSTAL-STRUCTURE OF [MO2(MU-ETA-5-ETA-5-C10H8)(MU-SC6H5)(ETA-5-C5H5)2][RE2(MU-SC6H5)3(CO)6]

New bridged fulvalene (Fv = mu-eta5 :eta5-C10H8) binuclear molybdenum(III) and tungsten(III) compounds were obtained from the reaction of [M(eta5-C5H5)2(SC6H5)2] (M = Mo or W) with dirhenium decacarbonyl. The complex [Mo2Fv(mu-SC6H5)CP2][Re2(mu-SPh)3(CO)6] WaS characterized by single crystal X-ray diffraction. The cation [Mo2Fv(mu-SC6H5)Cp2)+ showed a relatively rigid [Mo2FvCp2] unit with an Mo-S-Mo angle of 83.88(7)-degrees, M-S distances 2.442(2) and 2.450(2) A and a Mo ... Mo distance of 3.256(l) angstrom. In the [Re2(mu-SPh)3(CO)6]- anion, each metal atom has an octahedral environment (three carbonyl and three thiolate groups) with the two octahedra sharing the face containing the sulphur donor atoms (Re-S-Re angles from 86.63(8) to 86.83(8)-degrees). The Re ... Re distance of 3.457(l) A is long. Extended Huckel molecular orbital calculations were done in order to understand the nature of the metal-metal interaction in the cation and some related complexes. Although the Mo ... Mo distance is relatively long, there is a strong interaction between the two d3 metal atoms, assigned to a sigma bond, which leads to diamagnetic behaviour (the anion with two d6 Re(I) centres is also diamagnetic).