Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways
作者:Lauren N. Mendelsohn、Connor S. MacNeil、Lei Tian、Yoonsu Park、Gregory D. Scholes、Paul J. Chirik
DOI:10.1021/acscatal.0c05136
日期:2021.2.5
containing radical clocks, and experiments probing relative rates supports a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt–hydrogen bond of 54 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of
易于制备的配位饱和钴(I)预催化剂(R,R)-(iPr DuPhos)Co(CO)2 H((R,R)-iPr DuPhos =(+)-1,2 -bis [(2 R,5 R)-2,5-二异丙基膦酰基苯)。在加热到100°C时,观察到一系列烯烃的有效转化率,而在35°C的蓝光照射下,钴催化剂的催化性能显着提高。这种改进的反应性使得末端,二和三取代的烯烃,炔烃和羰基化合物的氢化成为可能。氘标记研究,含自由基钟的烯烃加氢以及探索相对速率的实验相结合,支持了在热条件下通过54 kcal / mol相对较弱的钴氢键实现的氢原子转移途径。相反,[R ,- [R )- (的iPr DUPHOS)的Co(CO)2 H.这些结果证明催化与地球丰富的金属的通用性为涉及开放与封闭壳中间体可通过能量源来切换路径。