Influence of Interligand Interactions and Core-Charge Distribution on Gold Cluster Stability: Enthalpy Versus Entropy

Abstract

Understanding of the factors underlying the formation, reactivity and stability of ligated gold clusters is necessary for directing the synthesis of atomically-precise clusters with tailored properties. In this study we employ time- and energy-resolved surface induced dissociation (SID) experiments in conjunction with density functional theory calculations which provide molecular-level insight into ligand-gold cluster interactions and the ligand exchange process. Ligated gold clusters were prepared in solution by reduction of a gold salt precursor containing triphenylphosphine (PPh3). Subsequent exchange reactions of the preformed clusters with methyldiphenylphosphine (MePPh2) ligands generated a distribution of mixed-phosphine gold clusters. The results indicate that MePPh2 exhibits lower binding energy than PPh3 and both ligands are more strongly bound in the mixed-ligand clusters than in any of the pure PPh3-ligated gold clusters studied to date. Along with an increase in ligand binding energies, the m...