Substrate Redox Non-innocence Inducing Stepwise Oxidative Addition Reaction: Nitrosoarene C–N Bond Cleavage on Low-Coordinate Cobalt(0) Species

The reactions of
nitroso­arenes with transition-metal species
are fundamentally important for their relevance to metal-catalyzed
transformations of organo-nitrogen compounds in organic synthesis
and also the metabolization of nitroarenes and anilines in biology.
In addition to the well-known reactivity of metal-mediated N–O
bond activation and cleavage of nitroso­arenes, we present herein
the first observation of a nitroso­arene C–N bond oxidative
addition reaction upon the interaction of a three-coordinate cobalt(0)
species [(IPr)­Co­(vtms)2] with 2,4,6-tri­(tert-butyl)-1-nitroso-benzene (Ar*NO). The reaction produces a cobalt
nitrosyl aryl complex, [(IPr)­Co­(Ar*)­(NO)] (1),
with a bis­(nitroso­arene)cobalt complex, [(IPr)­Co­(η2-ONAr)­(κ1-O-ONAr)] (2), as an intermediate. Spectroscopic characterizations, DFT
calculations, and kinetic studies revealed that the redox non-innocence
of nitroso­arene induces a stepwise pathway for the C–N
bond oxidative addition reaction.