The bismuth phosphanides Bi(PR₂)₃: sources of phosphanyl radicals, P-inversion, and reversible olefin insertion

Understanding and controlling radical reactions for selective transformations under mild conditions remains one of the key challenges in synthetic chemistry. The detailed investigation of previously inaccessible structural motifs can grant important insights, provide new stimuli, and offer innovative strategies for further developments in the field. In this respect, the controlled release of simple phosphanyl radicals [PR₂]˙ from metal precursors is significantly underdeveloped to date. Here we report the synthesis, isolation, and full characterization of a series of homoleptic parent bismuth phosphanides [Bi(PRR')₃] (R, R' = alkyl). The ability of these compounds to release phosphanyl radicals under mild conditions is demonstrated, revealing an unprecedented radical pathway for the inversion of phosphorus atoms, enabling ethylene activation, and facilitating reversible olefin insertion into Bi-P bonds.