Darensbourg Donald J, Fitch Shawn B
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Inorg Chem. 2007 Jul 9;46(14):5474-6. doi: 10.1021/ic7007842. Epub 2007 Jun 13.
A tetramethyltetraazaannulene complex incorporating a chromium(III) metal center has been shown to be highly active toward the copolymerization of cyclohexene oxide and carbon dioxide to afford poly(cyclohexene carbonate) in the presence of [PPN]N3 [PPN+=bis(triphenylphosphoranylidene)ammonium] as a cocatalyst. An asymptotical rate increase was observed, leveling at 2 equiv of cocatalyst with a maximum turnover frequency of 1300 h(-1) at 80 degrees C. A benefit of this new catalyst system over that of the previously studied less-active (salen)CrX system is that the (tmtaa)CrCl catalyst has a much lower propensity toward the formation of a cyclic carbonate byproduct throughout the copolymerization reaction.
已证明，一种含有铬（III）金属中心的四甲基四氮杂环壬烯配合物在作为助催化剂的[PPN]N3[PPN += 双（三苯基磷亚基）铵]存在下，对环氧环己烷和二氧化碳的共聚反应具有高活性，可生成聚（环己烯碳酸酯）。观察到速率呈渐近增加，在2当量助催化剂时趋于平稳，在80℃下最大周转频率为1300 h⁻¹。这种新催化剂体系相对于先前研究的活性较低的（salen）CrX体系的一个优点是，（tmtaa）CrCl催化剂在整个共聚反应中形成环状碳酸酯副产物的倾向要低得多。
