Investigating Oxidative Addition Mechanisms of Allylic Electrophiles with Low-Valent Ni/Co Catalysts Using Electroanalytical and Data Science Techniques

The catalysis by a ir-allyl-Co/Ni complex has drawn significant attention recently due to its distinct reactivity in reductive Co/Ni-catalyzed allylation reactions. Despite significant success in reaction development, the critical oxidative addition mechanism to form the ir-allyl-Co/Ni complex remains unclear. Herein, we present a study to investigate this process with four catalysis-relevant complexes: Co(MeBPy)Br2, Co(MePhen)Br2, Ni-(MeBPy)Br2, and Ni(MePhen)Br2. Enabled by an electroanalytical platform, Co(I)/Ni(I) species were found responsible for the oxidative addition of allyl acetate. Kinetic features of different substrates were characterized through linear free-energy relation-ship (Hammett-type) studies, statistical modeling, and a DFT computational study. In this process, a coordination-ionization-type transition state was proposed, sharing a similar feature with Pd(0)-mediated oxidative addition in Tsuji-Trost reactions. Computational and ligand structural analysis studies support this mechanism, which should provide key information for next-generation catalyst development.

Automated summary

In this study, the critical oxidative addition mechanism of the ir-allyl-Co/Ni complex was investigated. It was found that Co(I)/Ni(I) species are responsible for the oxidative addition reaction. A coordination-ionization-type transition state mechanism was proposed, which was supported by computational and ligand structural analysis.