Mechanistic Studies on the Reversible Hydrogenation of Carbon Dioxide Catalyzed by an Ir-PNP Complex
Mechanistic Studies on the Reversible Hydrogenation of Carbon Dioxide Catalyzed by an Ir-PNP Complex
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DOI：
10.1021/om2010172
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发表时间：
2011-11
期刊：
影响因子：
2.8
通讯作者：
R. Tanaka;M. Yamashita;L. Chung;K. Morokuma;K. Nozaki
中科院分区：
文献类型：
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作者：
R. Tanaka;M. Yamashita;L. Chung;K. Morokuma;K. Nozaki
PNP连接的Ir(III)三氢化合物1在KOH水溶液中对二氧化碳加氢反应表现出最高的催化活性。当以三乙醇胺为碱时，催化加氢反应可在相同催化剂下调节为可逆过程，但以活性为代价。用密度泛函方法对二氧化碳加氢反应进行了理论研究，提出了两条相互竞争的反应路径：去质子化脱芳构化步骤或氢解步骤作为速率控制步骤。这一结果很好地解释了我们的实验观察，即催化循环取决于碱的强度和氢气压力。
The PNP-ligated iridium(III) trihydride complex 1 exhibited the highest catalytic activity for hydrogenation of carbon dioxide in aqueous KOH. The catalytic hydrogenation can be tuned to be a reversible process with the same catalyst at the expense of the activity, when triethanolamine was used as a base. Theoretical studies on the hydrogenation of carbon dioxide using DFT calculations suggested two competing reaction pathways: either the deprotonative dearomatization step or the hydrogenolysis step as the rate-determining step. The results nicely explain our experimental observations that the catalytic cycle is dependent on both the strength of the base and hydrogen pressure.