关键字：Rare earths, Tridentate ligands,Polymerization
A series of rare-earth metal alkyl complexes supported by a heteroscorpionate ligand were prepared and structurally characterized. X-ray diffraction analysis revealed that the heteroscorpionate ligand is face-capping on the rare-earth metal in k(3) mode, making the configuration of the afforded chalky! metal complexes similar to that of half-metallocenes. These complexes are capable of polymerizing methyl methacrylate, with the lutetium complex displaying the highest activity even at low temperature. The poly(methyl methacrylate) obtained is syndiotactically enriched with narrow molecular weight distribution.