Stereoselective semi-transfer hydrogenation of alkynes is highly challenging due to issues with cis/trans-isomerization and over-reduction. Similarly, achieving simultaneous hydrogenation of both C=O and C=C bonds in α,β-unsaturated ketones pose substantial challenges. A series of phosphine-free Ni(II), Mn(II), and Co(II)-based complexes bearing benzimidazole-based tri- and tetradentate ligands were synthesized. Among them, the nickel complexes exhibited superior reactivity in Z-selective semi-transfer hydrogenation of alkynes and dual transfer hydrogenation of chalcones using ammonia borane (AB). Selective and efficient transfer hydrogenation protocols were developed based on strategic ligand and catalyst designing. Cat. 4, having a bulkier ligand, facilitated Z-selective semi-transfer hydrogenation of alkynes, while Cat. 1 with a relatively less bulky ligand enabled the dual transfer hydrogenation of α,β- unsaturated ketones to saturated alcohols. Employing the mild, additive-free protocols, a broad range of synthetically valuable Z-alkenes and functionalized alcohols were smoothly obtained. Several control experiments, along with DFT calculations provided critical insights into the catalytic cycle.

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