Reductive hydrosilylation of CO₂ by catalysts based on environmentally benign metals such as zinc still presents an unmet challenge in terms of catalyst selectivity and activity. Here we show that tetra-coordinated neutral zinc siloxide complexes supported by the β-diketiminato ligand bearing a pendant amine arm exhibit unprecedentedly high catalytic activity toward the selective reduction of CO₂ by a hydrosilane to silyl formate. More significantly, this zinc catalyst system can also effectively catalyze the subsequent reduction of silyl formate into methoxysilane in quantitative yield. To understand the mechanism of the CO₂ hydrosilylation and the influence of the side arm, a series of catalytic active species (or intermediates), zinc hydrides, and formates, has been synthesized and structurally characterized; the relevant stoichiometric reactions and kinetic study were performed. DFT calculations were also carried out to determine the reaction profiles for the CO₂ hydrosilylation and to explain the relative activity of the zinc catalysts employed in this study. This combined experimental and theoretical study gives insights into the critical effects of the pendant amine donor arm and the size of the alkyl group of the amine on the relative energetics of the species involved in the proposed catalytic cycle.

中文翻译：

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侧臂扭曲对Zn催化的CO _2的氢甲硅烷基化还原具有很高的选择性和活性，从而将CO ₂还原为甲酸酯和甲醇当量

通过基于环境友好的金属如锌的催化剂的CO ₂的还原性氢化硅烷化在催化剂选择性和活性方面仍然存在未解决的挑战。在这里，我们显示了由带有侧链胺臂的β-二酮基氨基配体支撑的四配位中性氧化硅锌配合物，对氢硅烷选择性地将CO ₂选择性还原为甲酸甲硅酯具有前所未有的高催化活性。更重要的是，该锌催化剂体系还可以以定量收率有效地催化随后的甲硅烷基甲酸酯还原成甲氧基硅烷。了解CO ₂的机理合成了氢化硅化反应和侧臂，一系列催化活性物质（或中间体），氢化锌和甲酸酯的影响，并对其结构进行了表征；进行了相关的化学计量反应和动力学研究。还进行了DFT计算，以确定CO ₂氢化硅烷化的反应曲线，并解释了本研究中使用的锌催化剂的相对活性。结合实验和理论研究，深入了解了胺侧链供体的关键作用以及胺烷基的大小对拟议催化循环中相关物种的相对能的影响。