Synthesis, structure and catalytic activity comparison of tris‐ and tetracoordinated lanthanide amides

Abstract

Abstract Tetracoordinated lanthanide amides [(Me 3 Si) 2 N] 3 Ln (μ‐CI)Li(THF) 3 (Ln=La (1), Pr (2)) were synthesized by the reaction of anhydrous lanthanide(III) chlorides LnCl 3 (Ln=La, Pr) with 3 equiv. of lithium bis(trimethyl‐silyl)amide (Me 3 Si) 2 NLi in THF, followed by recrystallization from toluene. Sublimation of 1 and 2 afforded the triscoordinate lanthanide amides [(Me 3 Si) 2 N] 3 Ln (Ln=La, Pr). The crystal structure of 2 was determined by X‐ray diffraction analysis. The catalytic activity studies show that the tetracoordinate amides can be used as single‐component MMA (methyl methacrylate) polymerization catalysts, while the triscoordinate amides showed poor activity on h4MA polymerization under the same conditions.