Catalytic Hydrodefluorination via Oxidative Addition, Ligand Metathesis, and Reductive Elimination at Bi(I)/Bi(III) Centers

Herein, we report a hydrodefluorination reaction of polyfluoroarenes catalyzed by bismuthinidenes, Phebox-Bi(I) and OMe-Phebox-Bi(I). Mechanistic studies on the elementary steps support a Bi(I)/Bi(III) redox cycle that comprises C(sp(2))-F oxidative addition, F/H ligand metathesis, and C(sp(2))-H reductive elimination. Isolation and characterization of a cationic PheboxBi(III)(4-tetrafluoropyridyl) triflate manifests the feasible oxidative addition of Phebox-Bi(I) into the C(sp(2))-F bond. Spectroscopic evidence was provided for the formation of a transient Phebox-Bi(III)(4-tetrafluoropyridyl) hydride during catalysis, which decomposes at low temperature to afford the corresponding C(sp(2))-H bond while regenerating the propagating Phebox-Bi(I). This protocol represents a distinct catalytic example where a main-group center performs three elementary organometallic steps in a lowvalent redox manifold.

Automated summary

The study reports a hydrodefluorination reaction of polyfluoroarenes catalyzed by bismuthinidenes, involving a Bi(I)/Bi(III) redox cycle with C(sp(2))-F oxidative addition, F/H ligand metathesis, and C(sp(2))-H reductive elimination steps. Spectroscopic evidence supports the formation of a transient Phebox-Bi(III)(4-tetrafluoropyridyl) hydride during catalysis, which decomposes at low temperature to regenerate the propagating Phebox-Bi(I). This protocol highlights a unique catalytic example of a main-group center performing three elementary organometallic steps in a low-valent redox manifold.