Single‐Step Synthesis of NiI from NiII with H2

Chemists have long sought to regulate the reactivity of H2 , to yield hydride ions, hydrogen atoms, or electrons on demand. One source of inspiration for achieving this control is [NiFe]hydrogenase ([NiFe]H2 ase), which reacts with H2 to form various hydrogen active species such as NiIII hydride species, NiII hydride species, and NiI low-valent species. Chemists have attempted to synthesize these hydrogen active species not only as models for the active species of [NiFe]H2 ase, but also as electron transfer catalysts. However, the synthesis of NiI complex directly from H2 has not been reported. This paper reports the first example of a single-step synthesis of a NiI complex, via reaction of a NiII complex with H2 , stable for over 3 months at room temperature and we further demonstrate a reductive coupling of acridinium ions as part of a reaction cycle.