Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base bifunctional catalysts for synthesis of carbamates under solvent-free conditions

Heterobimetallic dinuclear lanthanide alkoxide complexes Ln(2)Na(8)(OCH2CH2NMe2)(12)(OH)(2) [Ln: I (Nd), II (Sm), III (Yb) and IV (Y)] were used as efficient acid-base bifunctional catalysts for the synthesis of carbamates from dialkyl carbonates and amines as well as the N-Boc protection of amines. The cooperative catalysts showed high catalytic activity and a wide scope of substrates with good to excellent yields under solvent-free conditions. The systems have shown higher catalytic activities due to the noteworthy synergistic interactions of Lewis acid center-Bronsted basic center. The comparison of catalytic efficiency between mono-and dinuclear heterobimetallic lanthanide alkoxide analogues was also investigated.