Tetravalent Metal Complexes as a New Family of Catalysts for Copolymerization of Epoxides with Carbon Dioxide

New tetravalent metal complexes with a trianionic [ONNO]-tetradentate ligand and an ancillary chloride ligand were synthesized as catalysts for the copolymerization of epoxides with carbon dioxide (CO2). All of the titanium, zirconium, germanium, and tin complexes were found to copolymerize epoxides with CO2. In particular, the copolymerization of propylene oxide with CO2 gave the almost-completely alternating copolymers by using titanium or germanium complexes. These results are the first example of the copolymerization using tetravalent metal complexes as a main component of catalysts.

本研究合成了一类带有三阴离子型[ONNO]-四齿配体与辅助氯离子配体的新型四价金属配合物，用作环氧烷烃与二氧化碳(CO₂)共聚反应的催化剂。经测试，所有钛、锆、锗及锡基配合物均可催化环氧烷烃与CO₂的共聚反应；尤为值得注意的是，采用钛或锗配合物催化环氧丙烷与CO₂的共聚反应时，可得到近乎完全交替的共聚物。上述成果为首例以四价金属配合物作为催化剂核心组分的共聚反应报道。