Gold(II) Trihalide Complexes from Organogold(III) Precursors

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Computational Chemistry

Background:

• Monoalkylgold(III) precursors, [CF3AuX3]−, are known compounds.
• Understanding the stability and reactivity of gold halide complexes is crucial in inorganic chemistry.

Purpose of the Study:

• To investigate the formation and properties of mononuclear gold(II) halide complexes, [AuX3]−, in the gas phase.
• To explore the reactivity and stability of these gold(II) species, including their propensity for disproportionation.

Main Methods:

• Collision-induced homolytic splitting of the Au-C bond in [CF3AuX3]− precursors to generate [AuX3]−.
• Density Functional Theory (DFT) calculations to determine the geometries of [AuX3]− complexes (X=F, Cl, Br, I).
• Analysis of the electronic structure and bonding in neutral AuX2 molecules and [AuX3]− anions.

Main Results:

• Mononuclear gold(II) halide complexes, [AuX3]−, were successfully formed in the gas phase.
• DFT calculations provided optimized geometries for the [AuX3]− series, revealing insights into their structural preferences.
• Neutral AuX2 molecules were identified as unsaturated, readily accepting an additional halide ligand.
• Homolytic splitting of an Au-X bond in [AuX3]− to form lower-valent [AuX2]− was found to be energetically favored over halide dissociation.

Conclusions:

• The gas-phase formation of gold(II) halide complexes via Au-C bond cleavage is feasible.
• The calculated geometries and electronic properties highlight the reactivity of these species.
• The observed preference for homolytic Au-X bond cleavage suggests that [AuX3]− complexes are prone to disproportionation.