Rogers, FergusCoote, Michelle2020-07-071932-7447http://hdl.handle.net/1885/205876To expand the scope for carbon-centered radical generation by electrochemical activation of adducts based on stable free radicals, a test set of six simple electron-rich Kuhn verdazyl derivatives in conjunction with nine different alkyl leaving groups has been computationally assessed. Like triazinyls, adducts of simple verdazyl derivatives functionalized with electron-donating substituents favor mesolytic cleavage to carbon-centered radicals under mild electrochemical potentials (−0.7 to −0.2 V vs Fc+/Fc). Electrochemical oxidation was found to reduce the bond dissociation Gibbs free energy (298 K in acetonitrile) by 70 kJ mol−1 on average, when comparing the homolytic cleavage pathway of the unoxidized adduct to the preferred mesolytic pathway of the oxidized adduct (i.e., to form either a verdazyl radical and a carbocation or a verdazyl cation and a carbon-centered radical). Considering the full thermochemical cycle, we illustrate that all the relevant free energy changes can be reduced to differences between the oxidation potentials of adducts and radicals, defining a series of criteria that govern the rational design of suitable candidates for oxidative carbon-centered radical cleavage. As a result of a tradeoff between promoting the oxidation of the adduct and enhancing the net reduction in BDFE upon oxidation, the best verdazyl derivatives for carbon-centered radical generation are those substituted with tBu substituentsThe authors gratefully acknowledge Mr. Alfred K. K. Fung for suggesting that we investigate the Kuhn verdazyls. M.L.C. gratefully acknowledges a Georgina Sweet ARC Laureate Fellowship (FL170100041) and generous allocations of supercomputing time on the National Facility of the Australian National Computational Infrastructure.application/pdfen-AU© 2019 American Chemical Society2019-07-2310.1021/acs.jpcc.9b062882020-06-23