Actinide Complexes Possessing Six-Membered N‑Heterocyclic Iminato Moieties: Synthesis and Reactivity

A novel class of
ligand systems possessing a six-membered 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.