Given that addition of TDAE proved important for obtaining good yields in the enantioselective e-NHK, mechanistic studies were carried out to determine the role of this additive. During the optimization process, a stoichiometric condition utilizing excess Cr(II) complex was found to give ee values comparable to the electrocatalytic system (Figure ). Addition of an acidic deuterium source to this reaction mixture led to formation of deuterated alkane 79 consistent with other reports of alkylative NHK-type reactions. The consistent ee between the stoichiometric system and the electrochemical system suggests that both the stoichiometric and catalytic conditions involve formation of the same putative alkylchromium species, and that TDAE is not required for formation of this intermediate. We hypothesized that in the electrochemical system, TDAE mediates the reduction of the L7•Cr III . This process might be more important with L7-coordinated Cr if the sterically encumbered chiral ligand imposes an additional kinetic barrier to reduction at the electrode surface.