A series of neutral rare earth metal amides with different metal-nitrogen bonds were synthesized and characterized. The selective catalytic activity and reactivity of the complexes incorporating different metal-nitrogen (Ln-N, Ln = rare earth metal) bonds were studied. Treatment of (Me 6), Sm ( 7)) incorporating different Ln-N bonds in good yields. Reaction of 6 or 7 with grease (Me 2 SiO) 3 in toluene produced the selective insertion products [C 6 H 5 N(Me 2 Si)N(C 6 H 5 )(Me 2 SiO)LnN(SiMe 3 ) 2 ] 2 (Ln = Yb (8), Sm ( 9)). The structures of complexes 1, 2, 4, 5, 8, and 9 were additionally determined by single-crystal X-ray analyses. Investigation of catalytic activity of the complexes indicated that the complexes displayed a high selectivity on cyclotrimerization or cyclodimerization toward isocyanates depending on the nature of the isocyanates. These catalysts have the advantages of a high reactivity and good selectivity toward isocyanates, easy preparation, low catalyst loading, and high conversion, as well as mild reaction conditions.

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