Two-Electron HCl to H2 Photocycle Promoted by Ni(II) Polypyridyl Halide Complexes
Two-Electron HCl to H2 Photocycle Promoted by Ni(II) Polypyridyl Halide Complexes
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DOI：
10.1021/ja408787k
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发表时间：
2013-12-18
影响因子：
15
通讯作者：
Nocera, Daniel G.
中科院分区：
文献类型：
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作者：
Powers, David C.;Anderson, Bryce L.;Nocera, Daniel G.
光化学HX分裂需要两个质子的管理和多电子光反应的执行。在这里，我们报告了一个光诱导的两个电子还原的聚吡啶镍（II）氯化物络合物，提供了一个路线H-2进化从盐酸。Ni络合物的激发态太短，不能直接参与HX活化，因此，激发态的光氧化还原介体被用于在Ni（II）中心活化HX。纳秒瞬态吸收（TA）光谱表明，激发态的聚吡啶的结果在光还原的自由基，能够介导HX激活通过产生一个Ni（I）中心卤素原子抽象。光生Ni（I）中间体的歧化提供Ni（II）和Ni（0）络合物。Ni（0）中心能够与HX反应以产生H-2和聚吡啶二氯化Ni（II），从而关闭从HCl产生H-2的光循环。
Photochemical HX splitting requires the management of two protons and the execution of multielectron photoreactions. Herein, we report a photoinduced two-electron reduction of a polypyridyl Ni(II) chloride complex that provides a route to H-2 evolution from HCl. The excited states of Ni complexes are too short to participate directly in HX activation, and hence, the excited state of a photoredox mediator is exploited for the activation of HX at the Ni(II) center. Nanosecond transient absorption (TA) spectroscopy has revealed that the excited state of the polypyridine results in a photoreduced radical that is capable of mediating HX activation by producing a Ni(I) center by halogen-atom abstraction. Disproportionation of the photogenerated Ni(I) intermediate affords Ni(II) and Ni(0) complexes. The Ni(0) center is capable of reacting with HX to produce H-2 and the polypyridyl Ni(II) dichloride, closing the photocycle for H-2 generation from HCl.