Highly Active Di- and Trimetallic Cobalt Catalysts for the Copolymerization of CHO and CO2 at Atmospheric Pressure

The synthesis and characterization of three new cobalt catalysts for the copolymerization of carbon dioxide and cyclohexene oxide are reported. All the complexes are extremely active at just 1 atm pressure of carbon dioxide, with very high selectivity for copolymerization and carbonate formation. The catalysts are dicobalt(II/II and II/III) and tricobalt(II/II/II) complexes coordinated by a macrocyclic, reduced “Robson” type ancillary ligand and by acetate groups. The complexes are significantly more active than their direct zinc analogues, which we attribute to the increased nucleophilicity of the cobalt−oxygen bond in the cobalt−carbonate propagating species. All three complexes are characterized using mass spectrometry, infrared and ultraviolet−visible spectroscopies, elemental analysis, and, for the tricobalt complex and mixed valence dicobalt species, single-crystal X-ray crystallography.

本研究报告了三种新型钴催化剂的合成与表征，旨在促进二氧化碳与环己烯氧化物的共聚合反应。所有这些催化剂在仅1个大气压的二氧化碳压力下展现出极高的活性，对共聚合反应及碳酸盐的形成具有极高的选择性。这些催化剂包括二钴(II/II和II/III)和三钴(II/II/II)配合物，它们通过一个宏环状的还原型“Robson”型辅助配体以及乙酸基团进行配位。与它们的直接锌类似物相比，这些配合物活性显著提高，我们将其归因于钴-氧键在钴-碳酸盐链增长物种中亲核性的增强。所有三种配合物均采用质谱、红外光谱和紫外-可见光谱、元素分析以及三钴配合物和混合价态的二钴物种的单晶X射线晶体学进行表征。