Enhanced Ammonia Oxidation Catalysis by a Low-Spin Iron Complex Featuring Cis Coordination Sites.
Enhanced Ammonia Oxidation Catalysis by a Low-Spin Iron Complex Featuring Cis Coordination Sites.
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具有顺式配位的低自旋铁配合物增强氨氧化催化作用。
DOI：
10.1021/jacs.1c02232
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发表时间：
2021-05-26
影响因子：
15
通讯作者：
Peters JC
中科院分区：
文献类型：
--
作者：
Zott MD;Peters JC
将氨作为太阳能燃料的目标推动了燃料电池应用的选择性氨氧化(AO)催化剂的发展。在这里，我们描述了一种铁介体的AO电催化剂，[(BpyPy2Me)Fe(MeCN)2]2+，它是迄今为止报道的分子体系中最高的转化率(TON)。为了改进我们最近报道的一种相关的铁-AO电催化剂[(TPA)Fe(MeCN)2]2+(TON为16)，目前的[(BpyPY2Me)Fe(MeCN)2]2+体系(TON为149)具有更强的电场、更刚性的辅助配体，保持顺式不稳定的位置和在Fe(II)状态下占主导地位的低自旋布居。后者被认为是为了减轻脱金属，从而减轻催化剂在催化条件下因存在大量过量氨而降解的情况。此外，与[(TPA)Fe(MeCN)2]2+相比，[(BpyPy2Me)Fe(MeCN)2]2+体系在较低的偏压(~250 mV)下表现出更快的声光速率(约50倍)。电化学数据与初始的E1净氢原子提取步骤相一致，该步骤提供了顺胺/胺配合物[(BpyPy2Me)Fe(NH2)(NH3)]2+，随后在E2处开始催化。理论计算表明，N-N键的形成可能通过多种热力学途径，包括还原消除和氨亲核攻击。综上所述，本研究强调了富含稀土的金属Fe是一种很有前途的金属，在金属介导型分子体系的声光催化中具有广阔的应用前景。
The goal of using ammonia as a solar fuel motivates the development of selective ammonia oxidation (AO) catalysts for fuel cell applications. Herein we describe an Fe-mediated AO electrocatalyst, [(bpyPy2Me)Fe(MeCN)2]2+, that exhibits the highest turnover number (TON) reported to date for a molecular system. To improve on our recent report of a related iron AO electrocatalyst, [(TPA)Fe(MeCN)2]2+ (TON of 16), the present [(bpyPy2Me)Fe(MeCN)2]2+ system (TON of 149) features a stronger-field, more rigid auxiliary ligand that maintains cis-labile sites and a dominant low-spin population at the Fe(II) state. The latter is posited to mitigate demetallation and hence catalyst degradation by the presence of a large excess of ammonia under the catalytic conditions. Additionally, the [(bpyPy2Me)Fe(MeCN)2]2+ system exhibits a substantially faster AO rate (ca. 50x) at significantly lower (~250 mV) applied bias compared to [(TPA)Fe(MeCN)2]2+. Electrochemical data are consistent with an initial E1 net H-atom abstraction step that furnishes the cis amide/ammine complex [(bpyPy2Me)Fe(NH2)(NH3)]2+, followed by the onset of catalysis at E2. Theoretical calculations suggest the possibility of N–N bond formation via multiple thermodynamically plausible pathways, including both reductive elimination and ammonia nucleophilic attack. In sum, this study underscores that Fe, an earth-abundant metal, is a promising metal for further development in metal-mediated AO catalysis by molecular systems.
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影响因子：
4.6
作者：
BUHR, JD;TAUBE, H
通讯作者：
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