Anodic Ascent to Rh ^V : Decrypting the Origin of Selectivity in the Electrochemical C−H/N−H Functionalization

Electrochemical C−H functionalization offers a powerful strategy for synthesizing olefinated products. However, the detailed mechanism and the origins of selectivity in electro-olefination remain elusive. Through comprehensive density functional theory calculations on an Rh-catalyzed electrochemical N−H/C−H olefination of benzamides, we have elucidated a catalytic cycle involving high-valent Rh(IV/V) states. This pathway supersedes the conventional Rh(III/I/III) cycle, which is rendered inoperative by a prohibitively high barrier of 63.8 kcal/mol. Anodic oxidation generates a critical Rh(V) species that significantly lowers the barriers for both N−H and arene C−H activation steps. As a result, the chemoselectivity is decisively controlled, favoring olefination over annulation by 12.0 kcal/mol. The observed inactivity of the Ir analogue stems from its diminished electrophilicity, which weakens essential catalyst−substrate interactions. Collectively, these computational insights demonstrate that the applied electrochemical potential serves not merely as an electron source but also as a strategic tool for accessing high-valent catalytic states. This work establishes a foundation for the rational, mechanism-driven design of electrocatalysts.