Selectivity is an essential aspect in catalysis. At present, the improvement of the selectivity for complex reactions with multiple pathways/products, for example the carbon dioxide reduction reaction (CO₂RR), can usually be achieved for only one pathway/product. It is still a challenge to reversibly modulate the selectivity between two reaction pathways or products of the CO₂RR by one catalyst. Here, we propose the reversible modulation of selectivity between two products via spin crossover. By employing first-principles calculations, six spin crossover molecular catalysts are found among 17 kinds of transition metal embedded porphyrin derivatives (ppy_TM), where the changes in axial ligand configurations can reversibly switch the spin state of catalysts between high spin and low spin. For ppy_Os and ppy_Ru, the alteration in spin state can effectively influence the reduction of CO₂ into either formic acid or carbon monoxide by changing the relative stability of the key intermediates *COOH and *HCOO.

中文翻译：

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通过配体驱动的自旋交叉可逆调节二氧化碳还原的选择性


选择性是催化的一个重要方面。目前，通常只需一个途径/产物即可提高具有多种途径/产物的复杂反应的选择性，例如二氧化碳还原反应 （CO₂RR）。用一种催化剂可逆地调节两种反应途径或 CO₂RR 产物之间的选择性仍然是一个挑战。在这里，我们提出了通过自旋交叉对两种产物之间的选择性进行可逆调制。通过第一性原理计算，在 17 种过渡金属嵌入卟啉衍生物 （ppy_TM） 中发现了 6 种自旋交叉分子催化剂，其中轴向配体构型的变化可以在高自旋和低自旋之间可逆地切换催化剂的自旋状态。对于 ppy_Os 和 ppy_Ru，自旋态的改变可以通过改变关键中间体 *COOH 和 *HCOO 的相对稳定性，有效地影响 CO₂ 还原成甲酸或一氧化碳。