To further explore the proposed interplay between Ni and Co in catalysis, we performed a stoichiometric reaction between (dtbbpy)Ni II (o-tol)I and benzyl chloride in the presence of excess TDAE and catalytic amounts of Co Pc (Table ). This resulted in the generation of the diarylmethane cross-product, (o-tolyl)(phenyl)methane, in 76% yield (Entry 1). No product formation, however, was observed without Co Pc in either the presence or absence of TDAE (Entries 2 & 3), consistent with our hypothesis that Co primarily activates the alkyl electrophile in catalysis. Furthermore, the use of stoichiometric Co Pc without TDAE also yielded no cross-product (Entry 4), suggesting that the activation of alkyl electrophiles occurs at a reduced Co center. In agreement with this proposal, the reduction potential of TDAE 2+/0 is more negative than that of the Co II/I couple of Co Pc . Lowvalent Co complexes similar to [Co I (Pc)] -are known to undergo oxidative addition with alkyl halides through an SN2 mechanism to form Co III (Pc)(Alk) species. In turn, these high valent Co III complexes can undergo homolysis of the Co III -Alk bond, which produces an alkyl radical and regenerates Co Pc . Further support for the proposal that Co Pc is capable of generating alkyl radicals in the presence of TDAE was obtained by performing an analogous radical trapping experiment using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as the radical acceptor instead of (dtbbpy)Ni II (o-tol)I. In a similar fashion to our experiment with (dtbbpy)Ni II (o-tol)I, trapping a Co III (Pc)(Alk) species. The Co III (Pc)(Alk) species is generated in an independent catalytic cycle through initial reduction of Co Pc to form an anionic [Co I (Pc)] -complex, which can react with an alkyl halide via an SN2 mechanism. Following radical capture at (dtbbpy)Ni II (Ar)X, a putative (dtbbpy)Ni III (Ar)(Alk)X species is produced, which rapidly reductively eliminates at the Ni III center to liberate the product and form a (dtbbpy)Ni I X species. Finally, we propose that the (dtbbpy)Ni I X species is reduced by TDAE to regenerate Ni 0 , closing the catalytic cycle. Further mechanistic work to explore all of the potential roles of Ni I species is ongoing.