Carbon Dioxide Reduction with Dihydrogen and Silanes at Low-Valent Molybdenum Terphenyl Diphosphine Complexes: Reductant Identity Dictates Mechanism
Carbon Dioxide Reduction with Dihydrogen and Silanes at Low-Valent Molybdenum Terphenyl Diphosphine Complexes: Reductant Identity Dictates Mechanism
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DOI：
10.1021/acscatal.1c02922
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发表时间：
2021-10
期刊：
影响因子：
12.9
通讯作者：
Joshua A. Buss;Naoki Shida;Tianyi He;T. Agapie
中科院分区：
文献类型：
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作者：
Joshua A. Buss;Naoki Shida;Tianyi He;T. Agapie
硅烷和氢atpara-terphenyl二膦负载的钼配合物的反应化学的二氧化碳（CO2）还原的背景下进行了探索。CO2氢化硅烷化通常通过甲硅烷基缩醛提供还原产物。然而，虽然硅烷氢化物复合物的特点是在本系统中，合成，光谱和动力学研究表明，C-O裂解CO2发生独立的硅烷。在它们的存在下，一个假定的钼氧中间体被假设进行O-原子转移，产生硅烷醇。相反，氢化化学确实通过能够插入CO2的中间体二氢化钼发生，以产生甲酸氢化物络合物。这个过程是可逆的;在二氮下缓慢脱嵌得到二氢化钼、η2-CO2和N2络合物的混合物。氢化钼甲酸盐是一种有效的预催化剂，可用于CO2加氢生成甲酸盐（在锂阳离子和碱的存在下）和甲酸脱氢生成CO2和氢气（在碱的存在下）。这两个催化过程的机理研究。
The reaction chemistry of both silanes and hydrogen atpara-terphenyl diphosphine-supported molybdenum complexes was explored within the context of carbon dioxide (CO2) reduction. CO2hydrosilylation commonly affords reduction products via silyl acetals. However, while silyl hydride complexes were characterized in the present system, synthetic, spectroscopic, and kinetic studies suggest C–O cleavage of CO2occurs independently of silanes. In their presence, a putative molybdenum oxo intermediate is hypothesized to undergo O-atom transfer, yielding silanol. In contrast, hydrogenation chemistry does occur through an intermediate molybdenum dihydride capable of inserting CO2to yield a formate hydride complex. This process is reversible; slow deinsertion under dinitrogen affords a mixture of molybdenum dihydride, η2-CO2, and N2complexes. The molybdenum hydride formate species is a competent precatalyst for both CO2hydrogenation to formate (in the presence of lithium cations and base) and formic acid dehydrogenation to CO2and hydrogen (in the presence of base). Mechanistic studies of both catalytic processes are presented.