The previously discussed isomerization reactions are net-redox-neutral transformations. Therefore, a substoichiometric amount of cobalt hydride is needed to proceed efficiently since the active catalyst is regenerated during the reaction pathway (vide infra). Alternatively, cobalt-hydride chemistry can be used to reduce unsaturated systems. Such reactions, by definition, will require "stoichiometric" electrons to be added with the right tuning of the proton source and cobalt complex to achieve the desired transformation. As a proof of concept, using e-HAT logic, a new e-HAT set of conditions for Z-selective alkyne semi-reduction using HFIP as the hydride surrogate was developed. To place this into context, the most frequently employed reagents (i.e. outside a glove-box) to achieve such a reaction on unactivated (non-conjugated) alkynes involve the use of Pd (Lindlar) catalysis and diimide. For such selectivity, the 6,6'-dimethyl-bpy ligand combined with CoBr2 revealed the best reactivity delivering high Z-selectivity and minimal over-reduction (Conditions C, see SI for optimization). With this new set of conditions in hand, a range of substituted alkynes could be reduced with e-HAT to provide Z-alkenes in good yield (Table ) rapidly. Boc-protected amines (32), pyridines (33), ethers (34), free and silyl-protected alcohols (36, 41), aryl chlorides (37), aryl-BPin (38), carbonyls (39, 42), alkenes (39), and phosphates (40) were all tolerated. The highest Z/E selectivity was observed with primary-, secondary-, and tertiary carbons adjacent to the alkyne moiety. However, the process was less selective with quaternary carbons adjacent to the alkyne (see 43 and 44), presumably due to the increased steric hindrance surrounding the putative cobalt-alkene intermediate.