Elucidating metal (Zr, Hf, Th, U)-hydride covalency using 1H NMR chemical shifts and density functional calculations

Metal-ligand covalency is not fully understood for the actinides and studies comparing group IV transition metals with isostructural Th and U complexes are limited. Herein, we report the synthesis and characterization of [(C₅Me₅)₂(2,6-iPr₂C₆H₃O)M(H)], M = Hf, Th, and U, which can be compared to the previously reported Zr analog, to explore the differences between transition metal and actinide bonding situations. The ¹H NMR chemical shifts of each complex, including the paramagnetic U(IV) compound, showed reasonable agreement with the computed shifts and benchmark the covalency of the metal-hydride bonds.