西班牙国家研究委员会和塞维利亚大学Campos Jess团队报道了，在烯烃异构化中开壳Ir(II)/Ir(IV) 氧化还原对的性能优于 Ir(I)/Ir(III) 氧化还原对。相关研究成果发表在2025年1月20日出版的《自然—化学》。

基于第一排过渡金属的开壳体系，及其在各种催化过程中的参与得到了很好的探索。相比之下，贵过渡金属的单核开壳配合物仍然不发达。对于Ir^II复合物来说尤其如此，因为关于它们在催化中的应用的可用信息非常有限。

该文中，研究表明，一个以C₆H₃-2,6-（OP（^tBu）₂）₂（POCOP）钳形配体为特征的Ir^II金属自由基家族有效地催化了烯烃异构化——烷烃复分解的关键步骤——其活性比Ir^I对应物高20倍。

计算研究表明，由于氧化加成和还原消除步骤的屏障减少，Ir^II/Ir^IV氧化还原循环比传统的Ir^I/Ir^III途径具有更快的动力学。因此，该研究提出了一种涉及Ir^II/Ir^IV对的氧化还原催化剂，突出了贵金属系统超越传统氧化还原循环的能力。这些发现强调了扩大催化设计原则的必要性，特别是对于铂族金属。

附：英文原文

Title: An open-shell Ir(II)/Ir(IV) redox couple outperforms an Ir(I)/Ir(III) pair in olefin isomerization

Author: Pita-Milleiro, Alejandra, Hidalgo, Nereida, Moreno, Juan J., Fernndez, Israel, Campos, Jess

Issue&Volume: 2025-01-20

Abstract: Open-shell systems based on first-row transition metals and their involvement in various catalytic processes are well explored. By comparison, mononuclear open-shell complexes of precious transition metals remain underdeveloped. This is particularly true for IrII complexes, as there is very limited information available regarding their application in catalysis. Here we show that a family of IrII metalloradicals, featuring a C6H3-2,6-(OP(tBu)2)2 (POCOP) pincer ligand, effectively catalyses olefin isomerization—a key step in alkane metathesis—exhibiting up to 20 times higher activity than their IrI counterparts. Computational studies reveal that the IrII/IrIV redox cycling enables faster kinetics than the traditional IrI/IrIII pathway owing to reduced barriers for the oxidative addition and reductive elimination steps. Thus, this study presents a redox catalyst involving an IrII/IrIV pair, highlighting the capabilites of precious-metal systems that extend beyond traditional redox cycles. These findings emphasize the need for expanding catalytic design principles, especially for platinum-group metals.

DOI: 10.1038/s41557-024-01722-7

Source: https://www.nature.com/articles/s41557-024-01722-7