Gas Phase Formation, Structure and Reactivity of Gold Cluster Ions

Abstract

With the advent of electrospray ionisation (ESI) and matrix-assisted laser desorption ionisation (MALDI), mass spectrometry (MS) is now routinely used to establish the molecular formulae of gold nanoclusters (AuNCs). ESI-MS has been used to monitor the solution phase growth of AuNCs when gold salts are reduced in the presence of phosphine or thiolate ligands. Beyond this analytical role, over the past 2 decades MS-based methods have been employed to examine the fundamental properties and reactivities of AuNC ions. For example, ion mobility and spectroscopic measurements may be used to assign structures; thermochemical data provides important information on ligand binding energies; unimolecular chemistry can be explored; and ion-molecule reactions with various substrates can be used to probe catalysis by AuNC ions. MS can also be used to monitor and direct the synthesis of AuNC bulk material either by guiding solution phase synthesis conditions or by soft landing a beam of mass-selected (i.e. monodisperse) AuNC ions onto a surface. This review showcases all areas in which mass spectrometry has played a role in AuNC science.

Binding of multiple SO2 molecules to small gold cluster anions (AuN−, AuNOH−, N = 1‐8)

“…Oxide‐supported gold nanoparticles catalyze a variety of reactions, and recent work has been focused on the potential of these catalysts to react with SO 2 , as well as to understand how SO 2 can hinder the ability of the catalysts to perform other reactions . Attempts have also been made to gain a more basic understanding of the catalytic activity by relating the reactivity of gas‐phase gold clusters to that of the supported gold catalysts . Previous studies with gas‐phase gold clusters have shown that the global charge is related to the adsorption ability, with anions showing particularly interesting activity .…”

Probing the binding and activation of small molecules by gas-phase transition metal clustersviaIR spectroscopy

“…The literature about coinage metal (Cu, Ag, Au) clusters reacting with O 2 (and other molecules) has been evaluated several times more recently. 11 d ,29 d – f ,252 Anionic coinage clusters exhibit a pronounced odd/even oscillation of the reaction rate that is anti-correlated with the electron binding energies of the clusters. The even-numbered coinage cluster anions M 2 n − are open-shell due to the d 10 s 1 atomic configurations and typically show lower electron binding energies than their neighboring sizes.…”