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Catalytic Dehydrogenation of Alkanes by PCP–Pincer Iridium Complexes Using Proton and Electron Acceptors
ACS Catalysis ( IF 12.9 ) Pub Date : 2021-02-22 , DOI: 10.1021/acscatal.0c05160
Arun Dixith Reddy Shada 1 , Alexander J. M. Miller 2 , Thomas J. Emge 1 , Alan S. Goldman 1
Affiliation  

Dehydrogenation to give olefins offers the most broadly applicable route to the chemical transformation of alkanes. Transition-metal-based catalysts can selectively dehydrogenate alkanes using either olefinic sacrificial acceptors or a purge mechanism to remove H2; both of these approaches have significant practical limitations. Here, we report the use of pincer-ligated iridium complexes to achieve alkane dehydrogenation by proton-coupled electron transfer, using pairs of oxidants and bases as proton and electron acceptors. Up to 97% yield was achieved with respect to oxidant and base, and up to 15 catalytic turnovers with respect to iridium, using t-butoxide as base coupled with various oxidants, including oxidants with very low reduction potentials. Mechanistic studies indicate that (pincer)IrH2 complexes react with oxidants and base to give the corresponding cationic (pincer)IrH+ complex, which is subsequently deprotonated by a second equivalent of base; this affords (pincer)Ir which is known to dehydrogenate alkanes and thereby regenerates (pincer)IrH2.

中文翻译:

使用质子和电子受体的PCP-品位铱络合物对烷烃的催化脱氢

脱氢得到烯烃为烷烃的化学转化提供了最广泛适用的途径。过渡金属基催化剂可以使用烯烃牺牲性受体或吹扫机制除去H 2,对烷烃进行选择性脱氢。这两种方法都有很大的实际局限性。在这里,我们报告使用钳连接的铱配合物,通过质子耦合电子转移,使用成对的氧化剂和碱作为质子和电子受体,实现烷烃脱氢。使用t,相对于氧化剂和碱,最高可达到97%的收率,相对于铱,最高可实现15次催化转化。-丁醇作为碱与各种氧化剂偶联,包括还原电位非常低的氧化剂。机理研究表明,(钳)IrH 2配合物与氧化剂和碱反应,生成相应的阳离子(钳)IrH +配合物,随后被第二当量的碱去质子化。这提供了已知的(钳)Ir,其使烷烃脱氢并由此再生(钳)IrH 2
更新日期:2021-03-05
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