Reactions of di- and poly-nuclear complexes. 17. Isolation and reactivity of μ-oxo dinuclear molybdenum (IV) thiolato-bridged complexes containing terminal and bridging chloride or bromide groups [(ν-C 5Me 5)MoX] 2(μ-X)(μ-O)(μ-SMe)(X Cl, Br); crystal structure of [(ν-C 5Me 5)MoBr] 2(μ-Br)(μ-O)(μ-SMe)

Abstract

The reaction of [ν-C 5Me 5Mo(CO) 3] 2 with allyl chloride in refluxing THF gives the mononuclear complex [( ν-C 5Me 5)MoCl 2( ν 3-C 3H 5(CO)] ( 1). Thermolysis of complex 1 in THF or toluene in presence of dimethyldisulfide affords the unexpected complex [(ν-C 5Me 5)MoCl] 2(μ-Cl)(μ-O)(μ-SMe) ( 2). Similar reactions are observed with allyl bromide and give the analogous bromide complex 3. X-ray analysis establishes that complex 3 contains a Mo 2(μ-Br)(μ-O)(μ-SMe) core and that the C 5Me 5 ligands are cis with respect to the MoMo axis, as are the terminal Br groups. The formally double MoMo bond is relatively long (2.755(1) Å). An approximate plane of symmetry normal to the MoMo bond passes through the bridging O, Br and S donor atoms and relates the two C 5Me 5MoBr units. Complexes 2 and 3 react with HSMe to afford the μ-oxo-bis(μ-thiolato) products [(ν-C 5Me 5)MoX] 2(μ-O)(μ-SMe) 2 (X  Cl ( 4), Br ( 5)) and the replacement of the chloride bridge in complex 2 by HSCH 2CH 2SH leads to [(ν-C 5Me 5)MoCl] 2(μ-O)(μ-SMe)(μ-SCH 2CH 2SH)] ( 6).