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Identifying Intermediates in Electrocatalytic Water Oxidation with a Manganese Corrole Complex
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-09-01 , DOI: 10.1021/jacs.1c05204 Xialiang Li 1 , Xue-Peng Zhang 1 , Mian Guo 2 , Bin Lv 1 , Kai Guo 1 , Xiaotong Jin 1 , Wei Zhang 1 , Yong-Min Lee 2 , Shunichi Fukuzumi 2 , Wonwoo Nam 1, 2 , Rui Cao 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-09-01 , DOI: 10.1021/jacs.1c05204 Xialiang Li 1 , Xue-Peng Zhang 1 , Mian Guo 2 , Bin Lv 1 , Kai Guo 1 , Xiaotong Jin 1 , Wei Zhang 1 , Yong-Min Lee 2 , Shunichi Fukuzumi 2 , Wonwoo Nam 1, 2 , Rui Cao 1
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Water nucleophilic attack (WNA) on high-valent terminal Mn-oxo species is proposed for O–O bond formation in natural and artificial water oxidation. Herein, we report an electrocatalytic water oxidation reaction with MnIII tris(pentafluorophenyl)corrole (1) in propylene carbonate (PC). O2 was generated at the MnV/IV potential with hydroxide, but a more anodic potential was required to evolve O2 with only water. With a synthetic MnV(O) complex of 1, a second-order rate constant, k2(OH–), of 7.4 × 103 M–1 s–1 was determined in the reaction of the MnV(O) complex of 1 with hydroxide, whereas its reaction with water occurred much more slowly with a k2(H2O) value of 4.4 × 10–3 M–1 s–1. This large reactivity difference of MnV(O) with hydroxide and water is consistent with different electrocatalytic behaviors of 1 with these two substrates. Significantly, during the electrolysis of 1 with water, a MnIV-peroxo species was identified with various spectroscopic methods, including UV–vis, electron paramagnetic resonance, and infrared spectroscopy. Isotope-labeling experiments confirmed that both O atoms of this peroxo species are derived from water, suggesting the involvement of the WNA mechanism in water oxidation by a Mn complex. Density functional theory calculations suggested that the nucleophilic attack of hydroxide on MnV(O) and also WNA to 1e–-oxidized MnV(O) are feasibly involved in the catalytic cycles but that direct WNA to MnV(O) is not likely to be the main O–O bond formation pathway in the electrocatalytic water oxidation by 1.
中文翻译：
用锰钴络合物鉴定电催化水氧化的中间体
建议对高价末端 Mn-oxo 物种进行水亲核攻击 (WNA) 以在天然和人工水氧化中形成 O-O 键。在此，我们报告了碳酸亚丙酯 (PC) 中Mn III三(五氟苯基) corrole ( 1 )的电催化水氧化反应。O 2是在 Mn V/IV电位下用氢氧化物生成的，但需要更高的阳极电位才能仅用水释放 O 2。合成的 Mn V (O) 配合物为1，二阶速率常数k 2 (OH – ) 为 7.4 × 10 3 M –1 s –1由1的 Mn V (O) 络合物与氢氧化物的反应测定，而它与水的反应发生得慢得多，k 2 (H 2 O) 值为 4.4 × 10 –3 M –1 s –1。Mn V (O) 与氢氧化物和水的这种大的反应性差异与1对这两种底物的不同电催化行为一致。值得注意的是，在1用水电解过程中，Mn IV-peroxo 物种通过各种光谱方法进行鉴定，包括 UV-vis、电子顺磁共振和红外光谱。同位素标记实验证实，这种过氧物种的两个 O 原子都来自水，这表明 WNA 机制参与了 Mn 络合物的水氧化。密度泛函理论计算表明，氢氧化物对 Mn V (O)的亲核攻击以及 WNA 对 1e –氧化的 Mn V (O)的亲核攻击可能参与催化循环，但 WNA 直接攻击 Mn V (O) 不太可能是电催化水氧化中主要的 O-O 键形成途径1 .
更新日期：2021-09-15
中文翻译：
用锰钴络合物鉴定电催化水氧化的中间体
建议对高价末端 Mn-oxo 物种进行水亲核攻击 (WNA) 以在天然和人工水氧化中形成 O-O 键。在此，我们报告了碳酸亚丙酯 (PC) 中Mn III三(五氟苯基) corrole ( 1 )的电催化水氧化反应。O 2是在 Mn V/IV电位下用氢氧化物生成的，但需要更高的阳极电位才能仅用水释放 O 2。合成的 Mn V (O) 配合物为1，二阶速率常数k 2 (OH – ) 为 7.4 × 10 3 M –1 s –1由1的 Mn V (O) 络合物与氢氧化物的反应测定，而它与水的反应发生得慢得多，k 2 (H 2 O) 值为 4.4 × 10 –3 M –1 s –1。Mn V (O) 与氢氧化物和水的这种大的反应性差异与1对这两种底物的不同电催化行为一致。值得注意的是，在1用水电解过程中，Mn IV-peroxo 物种通过各种光谱方法进行鉴定，包括 UV-vis、电子顺磁共振和红外光谱。同位素标记实验证实，这种过氧物种的两个 O 原子都来自水，这表明 WNA 机制参与了 Mn 络合物的水氧化。密度泛函理论计算表明，氢氧化物对 Mn V (O)的亲核攻击以及 WNA 对 1e –氧化的 Mn V (O)的亲核攻击可能参与催化循环，但 WNA 直接攻击 Mn V (O) 不太可能是电催化水氧化中主要的 O-O 键形成途径1 .
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