REACTIONS OF DINUCLEAR AND POLYNUCLEAR COMPLEXES .17. ISOLATION AND REACTIVITY OF MU-OXO DINUCLEAR MOLYBDENUM(IV) THIOLATO-BRIDGED COMPLEXES CONTAINING TERMINAL AND BRIDGING CHLORIDE OR BROMIDE GROUPS [(ETA-C5ME5)MOX](2)(MU-X)(MU-O)(MU-SME) (X=CL, BR) - CRYSTAL-STRUCTURE OF [(ETA-C5ME5)MOBR](2)(MU-BR)(MU-O)(MU-SME)

The reaction of [eta-C5Me5Mo(CO)(3)](2) with allyl chloride in refluxi ng THF gives the mononuclear complex [(eta-C5Me5)MoCl2(pi(3)-C3H5)(CO) ] (1), Thermolysis of complex 1 in THF or toluene in presence of dimet hyldisulfide affords the unexpected complex [(eta-C5Me5) MoCl](2)(mu-C l)(mu-O)(mu-SMe) (2). Similar reactions are observed with allyl bromid e and give the analogous bromide complex 3. X-ray analysis establishes that complex 3 contains a Mo-2(mu-Br)(mu-O)(mu-SMe) core and that the C5Me5 ligands are cis with respect to the Mo-Mo axis, as are the term inal Br groups. The formally double Mo-Mo bond is relatively long (2.7 55(1) Angstrom). An approximate plane of symmetry normal to the Mo-Mo bond passes through the bridging O, Br and S donor atoms and relates t he two C5Me5MoBr units, Complexes 2 and 3 react with HSMe to afford th e mu-oxo-bis(mu-thiolato) products [(eta-C5Me5)MoX](2)(mu-O)(mu-SMe)(2 ) (X = Cl (4), Br (5)) and the replacement of the chloride bridge in c omplex 2 by HSCH2CH2SH leads to [eta-C5Me5)MoCl](2)(mu-O)(mu-SMe)(mu-S CH3CH2SH)] (6).