A novel class of ligand systems possessing a sixmembered N-heterocyclic iminato [perimidin-2-iminato (PrRN, where R = isopropyl, cycloheptyl)] moiety is introduced. The complexation of these ligands with early actinides (An = Th and U) results in powerful catalysts [(PrRN)An(N{SiMe3)2}3] (3-6) for exigent insertion of alcohols into carbodiimides to produce the corresponding isoureas in short reaction times with excellent yields. Experimental, thermodynamic, and kinetic data as well as the results of stoichiometric reactions provide cumulative evidence that supports a plausible mechanism for the reaction. © 2017 American Chemical Society.