Concerted aryl-sulfur reductive elimination from PNP pincer-supported Co(iii) and subsequent Co(i)/Co(iii) comproportionation

Bryan J Foley; Chandra Mouli Palit; Nattamai Bhuvanesh; Jia Zhou; Oleg V Ozerov

doi:10.1039/d0sc01813a

Concerted aryl-sulfur reductive elimination from PNP pincer-supported Co(iii) and subsequent Co(i)/Co(iii) comproportionation

Chem Sci. 2020 May 19;11(23):6075-6084. doi: 10.1039/d0sc01813a. eCollection 2020 Jun 21.

Authors

Bryan J Foley¹, Chandra Mouli Palit¹, Nattamai Bhuvanesh¹, Jia Zhou², Oleg V Ozerov¹

Affiliations

¹ Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , Texas 77842 , USA . Email: ozerov@chem.tamu.edu.
² School of Science , Harbin Institute of Technology , Shenzhen 518055 , China . Email: jiazhou@hit.edu.cn.

Abstract

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'.