Catalytic Activity of trans-Bis(pyridine)gold Complexes.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Organic Synthesis

Background:

• Gold catalysis is a rapidly advancing field in chemistry.
• Methodological advancements in gold catalysis are hindered by limited mechanistic understanding, particularly for Au(III) processes.
• Bis(pyridine)-ligated gold complexes are key targets for mechanistic investigation.

Purpose of the Study:

• To systematically investigate the reactivity of bis(pyridine)-ligated Au(III) and Au(I) complexes.
• To elucidate the role of pyridine ligand electron density and strain in modulating catalytic activity.
• To advance the mechanistic understanding of gold-mediated organic transformations.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• X-ray crystallography
• Density Functional Theory (DFT) calculations
• Propargyl ester cyclopropanation of styrene

Main Results:

• Pyridine ligand electron density was found to modulate the catalytic activity of Au(III) complexes.
• Bidentate bis(pyridine)-Au(III) complexes were observed to form dimers to relieve ligand-induced strain.
• Bis(pyridine)Au(I) complexes were demonstrated to be catalytically active for the first time, with reactivity influenced by strain.

Conclusions:

• The electron density of pyridine ligands is a critical factor in controlling Au(III) catalytic activity.
• Ligand design in gold catalysis must consider potential strain, leading to dimerization in Au(III) complexes.
• The discovery of catalytically active bis(pyridine)Au(I) complexes opens new avenues in gold catalysis research.