<i>Z</i>‐Selective Semihydrogenation of Alkynes Catalyzed by a Cationic Vanadium Bisimido Complex

Early metal gets the H: Under 1 atm of H2, the vanadium complex 1 (PFTB=perfluoro-tert-butoxide) catalytically semihydrogenates alkynes to Z alkenes. Synthetic and DFT studies, in combination with H2/D2 and NMR experiments, indicate that H2 is activated by 1,2-addition to 1. Upon insertion of an alkyne into the VH bond of A, the product alkene and 1 are generated by the 1,2-α-NH-elimination of the alkenyl ligand.