Reactivity of Diazoalkanes with Tantalum(V) Complexes of a Tridentate Amido-Bis(phenolate) Ligand

While a dimethyltantalum(V) complex of the [ONOcat]3− ligand ([ONOcat]H3 = N,N-bis(3,5-di-tert-butyl-2-phenol)amine) reacted with diazoalkane to afford products of insertion into the Ta−Me bond, the dichlorotantalum(V) complex [ONOcat]TaCl2(OEt2) reacted with 2 equiv of Ph2CN2 to form the ketazine adduct [ONOcat]TaCl2(η2(N,N′)-Ph2CNNCPh2). When Ph2CN2 was added to the dichloride in neat styrene, catalytic carbene transfer was observed to form the corresponding cyclopropane