Aryl–X Bond-Forming Reductive Elimination from High-Valent Mn–Aryl Complexes

Abstract

C–X bond reductive elimination and oxidative addition are key steps in many catalytic cycles for C–H functionalization catalyzed by precious metals; however, engaging first row transition metals in these overall 2e– processes remains a challenge. Although high-valent Mn aryl species have been implicated in Mn-catalyzed C–H functionalization, the nature and reactivity of such species remain unelucidated. In this work, we report rare examples of stable, cyclometalated monoaryl MnIII complexes obtained through clean oxidative addition of Ar–Br to MnI(CO)5Br. These isolated MnIII–Ar complexes undergo unprecedented 2e– reductive elimination of the Ar–X (X = Br, I, and CN) bond and MnII induced by 1e– oxidation, presumably via transient reactive MnIV species. Mechanistic studies suggest a nonradical pathway.