Tetravalent Cerium Alkyl and Benzyl Complexes

High-valent cerium complexes of alkyl and benzyl ligands are unprecedented due to the incompatibility of the typically highly oxidizing Ce4+ ion and the reducing alkyl or benzyl ligand. Herein we report the synthesis and isolation of the first tetravalent cerium alkyl and benzyl complexes supported by the tri-tert-butyl imidophosphorane ligand, [NP(Bu-t)(3)](1-). The Ce4+ monoiodide complex, [Ce4+I(NP(tert-butyl)(3))(3)] (1-CeI), serves as a precursor to the alkyl and benzyl complexes, [Ce4+(Npt)(NP(tert-butyl)(3))(3)] (2-CeNpt) (Npt = neopentyl, CH2C(CH3)(3)) and [Ce4+(Bn)(NP(tert-butyl)(3))(3)] (2-CeBn) (Bn = benzyl, CH2Ph). The bonding and structure of these complexes are characterized by single-crystal XRD, NMR and UV-vis-NIR spectroscopy, cyclic voltammetry, and DFT studies.