Electron and Hydride Addition to Gold(I) Thiolate Oligomers: Implications for Gold-Thiolate Nanoparticle Growth Mechanisms

Electron and hydride addition to Au(I):SR oligomers is investigated using density functional theory. Cyclic and chain-like clusters are examined in this work. Dissociation to Au- ions and Au-n(SR)(n+1)(-) chains is observed after 2-4 electrons are added to these systems. The free thiolate (SR-) is rarely produced in this work; dissociation of Au- is preferred over dissociation of SR-. Electron affinities calculated in gas phase, toluene, and water suggest that the electron addition process is unlikely, although it may be possible in polar solvents. In contrast, hydride addition to Au(I):SR oligomers yields free thiols and complexes containing Au-Au bonds, which are plausible intermediates for gold nanoparticle growth. The resulting compounds can react to form larger nanoparticles or undergo further reduction by hydride to yield additional Au-Au bonds.