Determinant role of the electrogenerated reactive nucleophilic species on the selectivity during the reduction of CO2 catalyzed by metalloporphyrins,Journal of the American Chemical Society

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Determinant role of the electrogenerated reactive nucleophilic species on the selectivity during the reduction of CO2 catalyzed by metalloporphyrins
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-03-18 , DOI: 10.1021/jacs.7b11267
Adrien J Göttle ₁ , Marc T M Koper ₁

Affiliation

This work provides insights to understand the selectivity during the reduction of CO2 with metalloporphyrin (MP) catalysts. The attack of a nucleophile on the carbon of the CO2 appears as an important event that triggers the catalytic reaction, and the nature of this nucleophile determines the selectivity between CO (or further reduced species) and HCOOH/HCOO–. For MP, the possible electrogenerated nucleophiles are the reduced metal-center and the hydride donor species, metal-hydride and phlorin-hydride ligand. The reduced metal-center activates the CO2 with the formation of the metal–carbon bond, which then gives rise to the formation of CO. The hydride donor species trigger the CO2 reduction by the attack of the hydride on the carbon of the CO2 (formation of a C–H bond), which results in the formation of HCOOH/HCOO– (formation of the metal-bonded formate intermediate is not involved). The MP with the metals Ni, Cu, Zn, Pd, Ag, Cd, Ga, In, and Sn are predicted to only form the phlorin-hydride intermediate and are thus suitable to produce HCOOH/HCOO–. This agrees well with the available experimental results. The MP with the metals Fe, Co, and Rh can form both the reduced-metal center and the hydride donor species (metal-hydride and phlorin-hydride), and thus are able to form both CO and HCOOH/HCOO–. The production of CO for Fe and Co is indeed observed experimentally, but not for Rh, probably due to the presence of axial ligands that may hinder the formation of the metal-bonded intermediates and thus drive the CO2RR to HCOOH/HCOO– via the phlorin intermediate.

中文翻译：

金属卟啉催化 CO2 还原过程中电生成反应性亲核物质对选择性的决定性作用

这项工作为了解金属卟啉 (MP) 催化剂还原 CO2 过程中的选择性提供了见解。亲核试剂对 CO2 碳的攻击似乎是触发催化反应的重要事件，并且该亲核试剂的性质决定了 CO（或进一步还原的物质）和 HCOOH/HCOO– 之间的选择性。对于 MP，可能的电生成亲核试剂是还原的金属中心和氢化物供体物质、金属氢化物和弗洛林氢化物配体。还原的金属中心通过形成金属-碳键激活 CO2，然后形成 CO。氢化物供体物种通过氢化物攻击 CO2 的碳来触发 CO2 还原（形成C-H 键），从而形成 HCOOH/HCOO-（不涉及金属键合甲酸酯中间体的形成）。含有金属 Ni、Cu、Zn、Pd、Ag、Cd、Ga、In 和 Sn 的 MP 预计仅形成氢氟酸中间体，因此适合生产 HCOOH/HCOO–。这与现有的实验结果非常吻合。 MP 与金属 Fe、Co 和 Rh 可以形成还原金属中心和氢化物供体物质（金属氢化物和弗洛林氢化物），因此能够形成 CO 和 HCOOH/HCOO–。实验中确实观察到 Fe 和 Co 产生 CO，但 Rh 没有观察到，可能是由于轴向配体的存在可能阻碍金属键合中间体的形成，从而通过根皮苷驱动 CO2RR 生成 HCOOH/HCOO。中间的。

更新日期：2018-03-18

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