Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates
作者:Deguang Huang、Olga V. Makhlynets、Lay Ling Tan、Sonny C. Lee、Elena V. Rybak-Akimova、R. H. Holm
DOI:10.1021/ic200942u
日期:2011.10.17
bicarbonate product complexes [NiII(pyN2R2)(HCO3)]− having η1-OCO2H ligation. Fixation reactions follow second-order kinetics (rate = k2′[NiII–OH][CO2]) with negative activation entropies (−17 to −28 eu). Reactions were monitored by growth and decay of metal-to-ligand charge-transfer (MLCT) bands at 350–450 nm. The rate order R = Me > macro > Et > Pri > Bui > Ph at 298 K (macro = macrocylic pincer ligand)
含有末端羟基的平面络合物[Ni II(pyN 2 R2)(OH)] -可以容易地由N,N '-(2,6-C 6 H 3 R 2)-2,6-吡啶二甲酰胺酸盐制备(2-)三齿钳状配体(R 4 N)(OH)和Ni(OTf)2。这些配合物在DMF中的溶液二氧化碳干净和完全反应在CO的过程2的固定与形成碳酸氢盐产物配合物[镍II(PYN 2 R2)(HCO 3)] -具有η 1 -OCO2 H结扎。固定反应遵循具有负激活熵(-17至-28 eu)的二级动力学(速率= k 2 '[Ni II -OH] [CO 2 ])。通过在350–450 nm的金属至配体电荷转移(MLCT)谱带的生长和衰减来监控反应。298 K时的速率顺序R = Me>宏观> Et> Pr i > Bu i > Ph(宏观=大环钳形配体)反映了反应位点的空间位阻增加。这些复合物的固有的高反应性性质如下从ķ 2 '≈10 6中号-1小号-1对于R