Reversible C-CN Bond Cleavage by a Formal Dinickel(I) Hydride Cation.

An N-heterocyclic carbene (NHC) ligand supports a stable [NiH] core, formally dinickel(I). This diamagnetic cation complex features a bent hydride bridge and a Ni···Ni distance, 2.9926(5) Å, larger than two covalent radii.

Three-Electron Nickel(I)/Nickel(0) Half-Bond.

An (N-heterocyclic carbene)nickel(I) cation precursor reacts with the corresponding nickel(0) complex to form a dinickel(I,0) monocation. The Ni···Ni distance in this cation is 0.93 Å shorter than in the analogous dinickel(0) complex.