Detaching thiolates from copper and gold clusters: which bonds to break?

Area of Science:

• Computational chemistry
• Materials science
• Surface science

Background:

• Alkanethiolates are widely used in surface functionalization and nanomaterials.
• Understanding metal-thiolate interactions is crucial for designing novel electronic and catalytic devices.

Purpose of the Study:

• To investigate the interaction of alkanethiolates with small copper and gold clusters.
• To elucidate the electronic origins of the differential weakening of the S-C bond in copper versus gold systems.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Fragmentation energies of the S-C bond were calculated for various cluster sizes (n=1-9).
• Electronic structure analysis was performed to understand bonding and polarization effects.

Main Results:

• Copper clusters (Cu(n)) progressively weaken the S-C bond in alkanethiolates with increasing cluster size, reducing fragmentation energy from 2.9 eV (n=1) to 1.4 eV (n=9).
• This weakening is attributed to electron density polarization in the S-C bond induced by copper cluster bonding.
• Gold clusters (Au(n)) showed only a slight 10% destabilization of the S-C bond as n increased from 3 to 9.
• Relativistic effects were discussed as a potential origin for the observed differences between copper and gold.

Conclusions:

• Copper clusters significantly destabilize the S-C bond in alkanethiolates, a phenomenon not observed with gold clusters.
• The electronic structure and relativistic effects play a critical role in dictating the metal-thiolate interaction strength.
• These findings have implications for the design of metal-organic interfaces and catalysts.