Gold nanoparticles have been discovered to exhibit remarkable catalytic properties in contrast to the chemical inertness of bulk gold. A prerequisite to elucidate the molecular mechanisms of the catalytic effect of nanogold is a detailed understanding of the structural and electronic properties of gold clusters as a function of size. In this review, we describe joint experimental studies (mainly photoelectron spectroscopy) and theoretical calculations to probe the structural properties of anionic gold clusters. Electronic properties and structural evolutions of all known Aun− clusters as experimentally confirmed to date are summarized, covering the size ranges of n = 3–35 and 55–64. Recent experimental efforts in resolving the isomeric issues of small gold clusters using Ar-tagging, O2-titration and isoelectronic substitution are also discussed.
