Reductive Elimination of Diphosphine from a Thorium–NHC–Bis(phosphido) Complex

Abstract

The synthesis, characterization, and reductive elimination reactivity of a bis(NHC)borate-supported thorium bis(phosphido) complex (2Mes) is described. Treating 2Mes with 2,2′-bipyridine leads to the reductive elimination of dimesityldiphosphine (4) and the formation of the previously reported NHC–thorium–bpy complex (3). The kinetics of the bpy-induced reductive elimination were studied by 31P NMR and suggest the presence of an intermediate. Treatment with alternative oxidants also leads to diphosphine elimination, but the corresponding thorium species have not been isolated cleanly. Additional primary (2Ph) and secondary (2PPh2) Th–bis(phosphido) complexes were synthesized but do not demonstrate the same facile reductive elimination as 2Mes.