Design of transition metal complexes containing a P–E radical motif

Abstract

Recently, we have synthesized phosphane W(CO)₅ complexes containing a P–O–TEMP ligand motif as bench-stable precursors of thermally accessible phosphanoxyl complex radicals possessing a ligand with a P–O˙ group. In this work, extensive dispersion-corrected DFT calculations are used to explore both W(CO)₅ and Fe(CO)₄ phosphane complexes containing the P–E–TEMP ligands (E = O, S, NMe, and PMe) in order to reach thermally accessible radicals with a P–E˙ motif. Moreover, a more general single-electron transfer (SET) oxidation approach to synthesize such P–E˙ radicals via anionic precursors is disclosed. Furthermore, the tendencies for self-trapping and prototropic reactions of such radical complexes have been studied for the first time. Electronic structures and potential conversions of such P–E˙ radicals are discussed, thus paving the way to a broad range of transition metal radical complexes, including potential thermal radical initiators.