Hydrogenation of <i>N</i>-Heteroarenes Using Rhodium Precatalysts: Reductive Elimination Leads to Formation of Multimetallic Clusters
作者:Sangmin Kim、Florian Loose、Máté J. Bezdek、Xiaoping Wang、Paul J. Chirik
DOI:10.1021/jacs.9b09540
日期:2019.11.6
addi-tion, the hydrogenation of polyaromatic N-heteroarenes exhibited uncommon chemoselectivity. Studies into catalyst activation revealed that photochemical or thermal activation of (η5-C5Me5)Rh(bq)H induced C(sp2)-H reductive elimination and generated the bimetallic complex, [(η5-C5Me5)Rh(µ2,η2-bq)Rh(η5-C5Me5)H]. In the presence of H2 both of the (η5-C5Me5)Rh(N-C)H precursors and [(η5-C5Me5)Rh(µ2,η2-bq)Rh(η5-C5Me5)H]
描述了一种用于氢化 N-杂芳烃的铑催化方法。使用有机金属预催化剂 (η5-C5Me5)Rh(NC)H(NC = 2-苯基吡啶基 (ppy) 或苯并[h]喹啉基(bq))。此外,聚芳族N-杂芳烃的氢化表现出不寻常的化学选择性。对催化剂活化的研究表明,(η5-C5Me5)Rh(bq)H 的光化学或热活化诱导 C(sp2)-H 还原消除并生成双金属配合物 [(η5-C5Me5)Rh(µ2,η2-bq) Rh(η5-C5Me5)H]。在 H2 存在下,(η5-C5Me5)Rh(NC)H 前体和 [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H] 均转化为五金属氢化铑簇,(η5-C5Me5)4Rh5H7,其结构由核磁共振光谱、X射线和中子衍射确定。用每种分离的铑配合物进行吡啶氢化的动力学研究,以鉴定催化相关物质。数据与由未观察到的多金属簇促进的氢化催化最一致,其中形成 (η5-C5Me5)4Rh5H7