Remodeling of N‑Heterocyclic Iminato Ligand Frameworks for the Facile Synthesis of Isoureas from Alcohols and Carbodiimides Promoted by Organoactinide (Th, U) Complexes

A new class of actinide
complexes [(L)­An­(N­{SiMe3}2)3] (An
= Th or U) (Th1–Th3 and U1–U3) supported by highly nucleophilic
seven-membered N-heterocyclic iminato ligands were synthesized and
fully characterized by single-crystal X-ray diffraction. These complexes
were successfully exploited as powerful catalysts for the addition
of alcohols to carbodiimides to yield the corresponding desirable
isourea products at room temperature with short reaction times and
excellent yields. Thorough stoichiometric, thermodynamic, and kinetic
studies were carried out, allowing us to propose a plausible mechanism
for the catalytic reaction.