Sequential Oxidation and C-H Bond Activation at a Gallium(I) Center

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Gallium(I) compounds are relatively uncommon and exhibit unique reactivity.
• Oxidation of low-valent main group compounds can lead to reactive intermediates.
• C-H bond activation is a fundamental transformation in chemistry.

Purpose of the Study:

• To investigate the in situ oxidation of a gallium(I) precursor, NacNacGa.
• To characterize the resulting gallium oxide species and its reactivity.
• To elucidate the mechanism of C-H bond cleavage using computational methods.

Main Methods:

• In situ oxidation using N2O or pyridine oxide.
• Characterization of reaction products (gallium organyl hydroxides).
• Density Functional Theory (DFT) calculations to study reaction mechanisms.

Main Results:

• Generation of a labile monomeric gallium(III) oxide, NacNacGa(O).
• NacNacGa(O) effectively cleaves C-H bonds in aliphatic and aromatic substrates with donor sites.
• Formation of gallium organyl hydroxides as reaction products.
• DFT calculations reveal facile proton abstraction by the oxo ligand from C-H bonds, including sp2-hybridized centers.

Conclusions:

• The study demonstrates a novel route to C-H bond activation using a gallium(III) oxide intermediate.
• The mechanism involves proton abstraction by a highly reactive oxo ligand.
• Steric hindrance is proposed as the reason for the lack of reaction with aliphatic amines.