Foley Bryan J, Palit Chandra Mouli, Bhuvanesh Nattamai, Zhou Jia, Ozerov Oleg V
Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , Texas 77842 , USA . Email:
School of Science , Harbin Institute of Technology , Shenzhen 518055 , China . Email:
Chem Sci. 2020 May 19;11(23):6075-6084. doi: 10.1039/d0sc01813a. eCollection 2020 Jun 21.
This report discloses a combined experimental and computational study aimed at understanding C-S reductive elimination from Co(iii) supported by a diarylamido/bis(phosphine) PNP pincer ligand. Divalent (PNP)Co-aryl complexes could be easily oxidized to five-coordinate Co(iii) derivatives, and anion metathesis provided five-coordinate (PNP)Co(Ar)(SAr') complexes of Co(iii). In contrast to their previously described (POCOP)Co(Ar)(SAr') analogs, but similarly to the (PNP)Rh(Ar)(SAr') and (POCOP)Rh(Ar)(SAr') analogs, (PNP)Co(Ar)(SAr') undergo C-S reductive elimination with the formation of the desired diarylsulfide product ArSAr'. DFT studies and experimental observations are consistent with a concerted process. However, in contrast to the Rh analogs, the immediate product of such reductive elimination, the unobserved Co(i) complex (PNP)Co, un-dergoes rapid comproportionation with the (PNP)Co(Ar)(SAr') starting material to give Co(ii) compounds (PNP)Co-Ar and (PNP)Co-SAr'.
本报告披露了一项结合实验与计算的研究，旨在了解由二芳基氨基/双（膦）PNP钳形配体支持的Co（III）的C-S还原消除反应。二价（PNP）Co-芳基配合物可轻松氧化为五配位Co（III）衍生物，阴离子复分解反应提供了Co（III）的五配位（PNP）Co（Ar）（SAr'）配合物。与之前描述的（POCOP）Co（Ar）（SAr'）类似物不同，但与（PNP）Rh（Ar）（SAr'）和（POCOP）Rh（Ar）（SAr'）类似物相似，（PNP）Co（Ar）（SAr'）会发生C-S还原消除反应，生成所需的二芳基硫醚产物ArSAr'。DFT研究和实验观察结果与协同过程一致。然而，与Rh类似物不同，这种还原消除反应的直接产物，即未观察到的Co（I）配合物（PNP）Co，会与起始原料（PNP）Co（Ar）（SAr'）迅速发生歧化反应，生成Co（II）化合物（PNP）Co-Ar和（PNP）Co-SAr'。
