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

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Nickel Catalysis

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Nickel complexes are crucial in various catalytic transformations.
• Understanding metal-metal interactions is key to designing new catalysts.

Purpose of the Study:

• To synthesize and characterize a novel dinickel(I,0) monocation stabilized by NHC ligands.
• To investigate the structural and electronic properties of the dinickel species.
• To explore the reactivity of the dinickel complex in small molecule activation and C-C bond formation.

Main Methods:

• Synthesis of a nickel(I) precursor and a nickel(0) complex.
• Reaction of the precursor with the nickel(0) complex to form the dinickel(I,0) monocation.
• X-ray crystallography for solid-state structure determination.
• Density functional theory (DFT) calculations for electronic structure analysis.
• Reactions with carbon monoxide (CO), nitric oxide (NO), and aryl bromides.

Main Results:

• Formation of a dinickel(I,0) monocation with a Ni-Ni bond 0.93 Å shorter than in the analogous dinickel(0) complex.
• Solid-state structure reveals equivalent Ni centers, while DFT calculations indicate electronic localization.
• Reactions with CO and NO yield mononuclear carbonyl and nitrosyl complexes, respectively.
• Oxidative addition of an aryl bromide leads to C-arylation of the carbene ligands.

Conclusions:

• The synthesized dinickel(I,0) monocation exhibits unique structural and electronic properties.
• The complex demonstrates reactivity towards small molecules and undergoes C-arylation, highlighting its potential as a catalytic intermediate.