Polymerization of acrylonitrile was carried out using,for the first time,the lanthanide-sodium alkoxide clusters Ln2(OCH2CH2NMe2)12(OH)2Na8 [Ln=Yb (1),Nd (2) and Sm (3)] as single component catalysts.These heterobimetallic complexes exhibit high activity and give atactic polyacrylonitriles with high molecular weight.The polymerization temperature can be varied over the range ?78 to 50°C.The solvent has a substantial effect on the polymerization activity.The order of activity for solvents is DMF>DME≈toluene≈THF>hexane.
Two ytterbium complexes stabilized by phenoxy（quinolinyl）amide ligand 3,5-But2-2-OC6H2CH2N-8-C9H6N （L） were synthesized and characterized. Reaction of anhydrous YbC13 with 1 equiv, of LLi2 in THF gave the ytterbium chloride [LYbCI（THF）]2 （1） in 73% yield. A further reaction of complex 1 with equimolar of NaN（SiMe3）2 in THF afforded the unexpected heterobimetallic ＂ate＂-complex L2YbNa（THF）2 （2） via a ligand redistribution reaction. Complex 2 could also be prepared in high isolated yield by the reaction of anhydrous YbC13 with 2 equiv, of LNa2 generated in situ. Both complexes 1 and 2 were characterized by IR spectroscopy, elemental analysis, and sin- gle-crystal X-ray diffraction analysis. It was found that complex 2 was an effective catalyst for the addition reaction of aromatic amines to carbodiimides.
