Identifying a Terminal Nickel-Oxygen Complex Bearing an Unsymmetrical β‑Diketiminate Ligand

Area of Science:

• Inorganic Chemistry
• Bioinorganic Chemistry
• Organometallic Chemistry

Background:

• Nickel-oxygen species are crucial intermediates in biological nickel-dependent catalysis and enzymatic reactions.
• Understanding these species is vital for deciphering complex biological mechanisms.

Purpose of the Study:

• To synthesize and crystallographically characterize the first terminal nickel-oxygen complex with a tridentate ligand.
• To investigate the electronic structure and bonding characteristics of this novel nickel-oxygen species.

Main Methods:

• Synthesis of a novel nickel-oxygen complex featuring a tridentate N-aryl-N'-methylpyridyl β-diketiminate ligand.
• Crystallographic characterization to determine the complex's structure.
• Density Functional Theory (DFT) calculations to analyze electronic structure and bonding.

Main Results:

• Successful synthesis and crystallographic determination of the first terminal nickel-oxygen complex.
• The complex exhibits dual bonding characteristics, describable as nickel-oxo (Ni^III=O) or nickel-oxyl (Ni^II-O^•).
• DFT calculations and experimental data indicate a resonance hybrid bonding, predominantly favoring the Ni^II-O^• state.

Conclusions:

• This study reports the first terminal nickel-oxygen complex with a specific tridentate ligand.
• The complex's bonding is a hybrid of Ni^III=O and Ni^II-O^• states, with Ni^II-O^• being dominant.
• This work provides insights into the nature of nickel-oxygen intermediates relevant to biological systems.