Desulfurization and ring opening of thiirane induced by tantalocene trihydride complexes: synthesis, reactivity and X-ray structure of Cp′2Ta(S)(S-iPr) with Cp′=η5-C5H4tBu

Abstract The reaction of the tantalocene trihydride complexes Cp′ 2 TaH 3 1 (Cp′= η 5 -C 5 H 4 t Bu) or Cp″CpTaH 3 1′ (Cp″= η 5 -C 5 H 2 -1,2-Me 2 -4- t Bu) with propylene sulfide was found to proceed via an unprecedented sulfur transfer and regioselective ring opening reaction at once to yield sulfido-thiolato tantalocene complexes Cp′ 2 Ta(S)(S- i Pr) 2a whose structure has been determined by X-ray crystallography or Cp″CpTa(S)(S- i 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 (with HBF 4 ) and alkylation (with MeI) reactions occur at the terminal sulfur ligand, leading to [Cp′ 2 Ta(SH)(S- i Pr)]BF 4 4a , [Cp′ 2 Ta(SMe)(S- i 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- i Pr)( μ -S)W(CO) 5 7a (or 7 ′ a ) and Cp′( μ -S,S- i Pr)]W(CO) 4 8a (or 8′a ) were formed. Inversion of configuration at the bridging μ -S atoms has been observed at low temperature for 8a and has been studied by dynamic 1 H-NMR spectroscopy.