We sought to identify appropriate reagents to explore our strategy of inhibiting off-cycle reactivity at LNi II (Ar)X intermediates by using a weak homogeneous reductant and promoting productive radical capture through the use of a co-catalyst capable of generating a radical from an alkyl halide. An established method for activating an alkyl electrophile to generate an alkyl radical under reductive conditions is to use a Co catalyst. Based on its previous compatibility in CEC with heterogeneous Zn 0 or Mn 0 reductants, we selected Co II (Pc) (Co Pc ; Pc = phthalocyanine). Next, we selected the weak homogeneous reductant tetrakis(dimethylamino)ethylene (TDAE), which is known to be compatible with Ni-catalyzed reductive coupling reactions. Importantly, TDAE (E° = -0.57 V vs NHE) is a weaker reductant than Mn 0 (E° = -1.19 V vs NHE) or Zn 0 (E° = -0.76 V vs NHE), which should limit deleterious reduction of LNi II (Ar)X species (Figure ), but it is still capable of reducing Co Pc (vide infra) and the commonly utilized Ni catalyst (dtbbpy)Ni II Br2 ( bpy Ni; dtbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine). To test our strategy, we performed CEC reactions between 4-tert-butylbromobenzene and 1-bromo-3-phenylpropane using 2.5 mol% Co Pc , 120 mol% TDAE, and variable loadings of bpy Ni (Table ). We selected 1,4-dioxane as the solvent due its ability to stabilize intermediates of the type LNi II (Ar)X (see SI), which is crucial for efficient radical capture in our envisioned pathway. Gratifyingly, we observed yields ranging from 53-84% depending on the loading of bpy Ni, with the highest yield obtained at 1 mol% loading (Entry 3). Our data also highlight how the reaction can be simply optimized by varying the relative loadings of bpy Ni and Co Pc . When a bpy Ni loading below 1 mol% is utilized, reduced yields are obtained presumably because the rate of alkyl halide consumption is faster than the rate of aryl halide consumption as evidenced by the presence of unreacted aryl bromide when all of the alkyl bromide has been consumed (Entries 1 & 2). In contrast, when a bpy Ni loading above 1 mol% is utilized, lower yields are obtained because the rate of aryl halide consumption is faster than the rate of alkyl halide consumption as evidenced by the presence of unreacted alkyl bromide when all of the aryl bromide has been consumed (Entries 4 & 5). We suggest that these trends occur because the aryl electrophile is primarily activated by (Figure ). Further, this approach to optimization has not previously been utilized in reductive coupling reactions and provides potential advantages over methods where optimization is performed by empirical ligand and additive screening.