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-C 5H 4tBu

Abstract

The reaction of the tantalocene trihydride complexes Cp′ 2TaH 3 1 (Cp′= η 5-C 5H 4 t Bu) or Cp″CpTaH 3 1′ (Cp″= η 5-C 5H 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′ 2Ta(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′ 2Ta(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′ 2Ta(SH)(S- i Pr)]BF 4 4a, [Cp′ 2Ta(SMe)(S- i Pr)]I 5a; the reaction of 2b with EtI was found to yield [Cp′ 2Ta(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′ 2Ta(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 1H-NMR spectroscopy.