Charge-Separation in Uranium Diazomethane Complexes Leading to C−H Activation and Chemical Transformation

The reaction of diphenyldiazomethane with [(( t -BuArO)3tacn)UIII] (1) results in an η2-bound diphenyldiazomethane uranium complex. This complex exhibits unusual electronic properties as a charge-separated species with a radical anionic open-shell ligand, [(( t -BuArO)3tacn)UIV(η2-NNCPh2)] (2). Treating Ph2CN2 with a uranium complex that contains a sterically more demanding adamantane functionalized ligand, [((AdArO)3tacn)UIII] (3) results in an unprecedented C−H activation and nitrogen insertion to produce a five-membered heterocyclic indazole complex, [((AdArO)3tacn)UIV(η2-3-phen(Ind))] (5). X-ray crystallography and spectroscopic characterization of these two compounds show that the [(( t -BuArO)3tacn)UIV(η2-NNCPh2)] compound is a U(IV) complex with a radical anionic ligand, whereas [((AdArO)3tacn)UIV(η2-3-phen(Ind))] is a U(IV) f 2 species with a closed-shell ligand.