Desulfurization and ring opening of thiirane induced by tantalocene trihydride complexes: synthesis, reactivity and X-ray structure of Cp ' Ta-2(=S)(S-Pr-i) with Cp ' = eta(5)-(C5H4Bu)-Bu-t

The reaction of the tantalocene trihydride complexes Cp-2'TaH3 1 (Cp' = eta (5)-C5H4'Bu) or Cp"CpTaH3 1' (CP" = eta(5)-C(5)H2-1,2-Me-2-4-'Bu) with prop ylene sulfide was found to proceed via an unprecedented sulfur transfer and regioselective ring opening reaction at once to yield sulfido-thiolato tan talocene complexes Cp-2'Ta(=S)(S-'Pr) 2a whose structure has been determine d by X-ray crystallograpby or Cp"CpTa(=S)(S-'Pr) 2'a. Complex 1 reacts with ethylene sulfide to give Cp-2'Ta(=S)(S-Et)2b. The reactivity of 2a towards a variety of electrophilic moities has been investigated: protonation (wit h HBF,) and alkylation (with Mel) reactions occur at the terminal sulfur li gand, leading to [Cp-2'Ta(SH)(S-'Pr)]BF4 4a, [Cp-2'Ta(SMe)(S-'Pr)]I 5a; the reaction of 2b with EtI was found to yield [Cp-2'Ta(S-Et)(2)]I 6b. Complex 2a (or 2') binds the unsaturated organometallic fragments [W(CO)(5)] and [ W(CO)(4)]; the new heterobimetallic complexes Cp-2'Ta(S-'Pr)(mu-S)W(CO)(5) 7a (or 7'a) and Cp'(mu-S,S-'Pr)]W(CO)(4) 8a (or 8'a) were formed. Inversion of configuration at the bridging mu-S atoms has been observed at low tempe rature for 8a and has been studied by dynamic H-1-NMR spectroscopy. (C) 199 9 Elsevier Science S.A. All rights reserved.