"Oxidative addition" to a Zirconium(IV) redox-active ligand complex

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• Oxidative addition is a key reaction in organometallic chemistry, typically involving d-electron rich transition metals.
• d(0) transition-metal complexes are generally considered unreactive towards oxidative addition due to their electron configuration.

Purpose of the Study:

• To present a novel strategy enabling reactivity analogous to oxidative addition in d(0) transition-metal complexes.
• To explore the reaction of a zirconium(IV) complex with a redox-active ligand and chlorine gas.

Main Methods:

• Synthesis of a zirconium(IV) complex with a redox-active ligand (2,4-di-tert-butyl-6-tert-butylamidophenolate, ap).
• Reaction of the synthesized complex with chlorine gas.
• Characterization of the product using X-ray crystallography, electron paramagnetic resonance (EPR) spectroscopy, and SQUID magnetometry.

Main Results:

• A new zirconium(IV) complex, Zr(IV)(ap)(2)(THF)(2), was synthesized.
• Exposure to chlorine gas resulted in chlorine addition to the zirconium center.
• This addition occurred via one-electron oxidation of the ap ligands, forming a diradical product Zr(IV)Cl(2)(isq)(2).

Conclusions:

• Demonstrated a strategy to achieve oxidative addition-like reactivity in d(0) transition-metal complexes.
• Highlighted the role of redox-active ligands in facilitating unusual reactivity pathways.
• The characterized diradical product provides insights into the electronic structure and bonding in these systems.