Although the Ni-catalyst loading reported in this disclosure is usually 20 mol%, no deliberate effort was made to reduce the loading. In the case of gram scale coupling of 8 and 93, a 10 mol% loading was employed (delivering 17 in 80% yield), suggesting that much lower loadings of Ni are possible. The seven reaction classes disclosed in this report can each be individually studied to unearth their guiding mechanistic principles. As such, a definitive mechanism for redox-neutral radical cross-coupling using sulfonyl hydrazides is beyond the scope of this work. Nevertheless, we provide a general mechanistic picture focusing on C(sp 2 )-C(sp 3 ) bond formation that is consistent with findings made thus far, and literature precedent, as outlined in Figure (left). As is well precedented in the literature , mild base undoubtedly liberates a diazine species 103 from the starting hydrazide 102 (generated in situ from hydrazone 101 by PhSiMe2H reduction which is perhaps mediated by a Ni-H species). The exact order of events following diazine liberation is currently unclear. For instance, it is conceivable that the diazene decomposes via . In the latter case, the 5-exo-trig cyclisation was only partially complete before coupling resulting in a mixture of cyclized product 117 and its linear counterpart (not shown) in a 1:1.4 ratio, respectively. The Giese reaction depicted in Table to access 3 from 8 was facilitated with added Ni but in the absence of catalyst it was also observed in lower yield (46% vs. 23%, respectively).