Single oxygen-atom insertion into P-B bonds: on- and off-metal transformation of a borylphosphine into a borylphosphinite.

An oxygen atom is selectively inserted into the P-B bond of a borylphosphine (L1) by reaction with Me3 NO to afford the corresponding borylphosphinite (L2). This transformation can also be effected when L1 is coordinated to rhodium. The ν(CO) values for trans-[RhCl(CO)(L)2] reveal very different electronic properties for coordinated L1 and L2 which translate into the strikingly different performances of the complexes [RhCl(L)(cod)] (L= L1 or L2, cod=1,5-cyclooctadiene) in hydrosilylation and hydroboration catalysis.