Reactivity of [Cp*Re(η3-C3H5)(CO)2][BF4] towards oxygen, sulfur, nitrogen and carbon nucleophiles

Article abstract of DOI:10.1016/S0022-328X(96)06680-6

The nucleophilic addition of oxygen, sulfur, nitrogen and carbon nucleophiles to [Cp*Re(η³-C₃H₅)(CO)₂][BF₄] (1) has been investigated. In all cases, addition of the nucleophile to the allyl ligand in 1 was observed to result, giving the substituted propene complexes with general formula Cp*Re(CO)₂(²-C₃H₅R) (R = CH₃CO₂, C₂H₅S, C₆H₅S, NH₂, N₃, CHMe₂ and C₆H₅) and [Cp*Re(CO)₂]₂(η²;η²-C₃H₅S(CH₂)₃SC₃H₅). No product of attack at the central carbon was observed for any of the nucleophiles. In the cases where the nucleophile was NH^-₂ or C₆H₅Li, nucleophilic addition occurred either at the η³-allyl or at a CO ligand. At low temperature (-78-0°C) the CO was attacked and complexes with general formula Cp*Re(η³-C₃H₅)(CO)(COR) (R = NH₂ and C₆H₅) were produced. When R is C₆H₅, the product was stable and was observed along with the substituted propene complex in solution, but when NH^-₂ was used, the carbamoyl complex converted completely to the substituted propene complex at room temperature. A by-product of the method used to synthesize Cp Cp* Re(η²-C₃H₅SC₆H₅)(CO)₂ was a small amount of Cp*Re(η³-C₃H₅)(CO)(O₂CSC₆H₅) (7). The X-ray crystal structure of 7 has been determined.