Organoactinide complexes promoted catalytic addition of alcohols into carbodiimides

The synthesis of various thorium (IV) and uranium (IV) actinide complexes containing a seven-membered N-heterocyclic iminato ligand is presented. The complexes are obtained by the corresponding protonolysis reaction between the free ligand and the corresponding actinide metallacycle [(Me₃Si)₂N]₂An[κ²-(N,C)-CH₂Si(CH₃)₂-N(SiMe₃)] (An = Th or U). (Fig. 1).

The complexes were thoroughly studied in the addition reaction of several alcohols to carbodiimides, (Fig. 2) displaying high reactivity under mild reaction condition, despite the highly oxophilicity nature of the metals. The catalytic process provides not just an efficient route for the formation of carbon-oxygen bonds but indicates how to design the actinides or other highly oxophilic complexes to perform as catalysts with oxygen-containing substrates. Kinetic and thermodynamic studies were conducted in order to draw a plausible mechanism for the overall transformation.