Tracing hydrogen bonding Au···H-C at gold atoms: a case study

Area of Science:

• Organometallic Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Cyclometalated 6-benzylpyridines with gold(III) centers exhibit a boat conformation, similar to 9,10-dihydroanthracene.
• A short Au···H-C contact involving a pseudoaxial methyl group suggests a potential interaction, possibly Au(III)···H-C hydrogen bonding.

Purpose of the Study:

• To investigate the ground state structures and conformations of gold(III) cyclometalated complexes using quantum chemical calculations.
• To determine if the observed Au···H-C contact represents an attractive interaction or hydrogen bond.
• To explain the conformational behavior based on simple rules and compare with platinum(II) analogues.

Main Methods:

• Quantum chemical calculations utilizing the B3LYP/def2-TZVP level of theory.
• Analysis of ground state structures and conformations for gold(III) complexes with varying substituents (H, CH3) at the bridging carbon atom.

Main Results:

• The ground state structures and conformations of the studied gold(III) complexes are explained by simple conformation rules.
• No evidence was found to support the Au(III)···H-C contact as an attractive interaction.
• The observed interactions are comparable to those found in related platinum(II) systems.

Conclusions:

• Conformational preferences in these gold(III) complexes are governed by established rules.
• The short Au···H-C contact is not indicative of a significant attractive force or hydrogen bonding.
• Understanding these interactions provides context for similar Au(III)···H-X and Pt(II) systems.