Synthesis and structure of indenyl rhodium(I) complexes containing unsaturated phosphines: catalyst precursors for alkene hydroboration.

The indenyl compound (eta(5)-C(9)H(7))Rh(coe)(2) (1, coe = cis-cyclooctene) has been prepared as a thermally stable alternative to the diethylene derivative (eta(5)-C(9)H(7))Rh(eta(2)-H(2)C[double bond, length as m-dash]CH(2))(2). Compound 1 reacts with unsaturated phosphines Ph(2)PR (R = CH[double bond, length as m-dash]CH(2), 2; CH(2)CH=CH(2), 3; and C triple bond C-tert-Bu, 4) to give complexes of the type (eta(5)-C(9)H(7))Rh(Ph(2)PR)(2), where bonding occurs through the phosphorus atom. Addition of Ph(2)PC triple bond CPPh(2) to 1 gave the dimer [(eta(5)-C(9)H(7))Rh(micro-Ph(2)PC triple bond CPPh(2))](2) (5). Solution and solid state data showed that these new phosphine complexes have only a moderate amount of distortion within the indenyl ring. These compounds were found to catalyse the hydroboration of vinylarenes and the first example of an internal hydroboration of diphenylvinylphosphine has been reported.