Hydrogen atom transfer in alkane thiol-gold cluster complexes: A density functional theory study

Alkane thiols, RSH, are commonly used in aqueous solution to stabilize and prevent aggregation of gold clusters, Aun. Initially a RSH-Aun complex is formed and, subsequently, there is hydrogen atom transfer to form a RSAunH complex. We examine the energetics of this process for small gold clusters, with n = 1–4 and short-chain thiols with R = H, CH3, and CH3CH2, using density functional theory. A pseudopotential was employed to account for the large relativisitic effects exhibited by gold. Equilibrium geometries and vibrational frequencies of the RSH-Aun and RSAunH complexes were obtained, as well as thermo-chemical values for the transfer of a hydrogen atom from sulphur to gold.