C-H···Au^- Interaction: To Be or Not to Be a Genuine Hydrogen Bond?

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• The role of gold ions in C-H hydrogen bonding is not fully understood.
• Experimental data on the strength of C-H···Au hydrogen bonds is limited.

Purpose of the Study:

• To experimentally determine the bond strength of C-H···metal hydrogen bonds.
• To clarify the physical nature of C-H···Au interactions.

Main Methods:

• Gas-phase photoelectron velocity-map imaging spectroscopy.
• Density Functional Theory (DFT) calculations.
• Energy-decomposition analysis.

Main Results:

• Measured interaction strengths: 0.43 eV for Cu⁻···CH₃CN and 0.51 eV for Au⁻···CH₃CN.
• Electrostatic interactions dominate, contributing ~60% to the total binding energy.
• Established benchmark values for C-H···metal hydrogen bond strengths.

Conclusions:

• Gold ions act as effective proton acceptors in C-H hydrogen bonds.
• The findings provide crucial data for understanding non-covalent interactions involving metals.