Charge-induced dipole vs. relativistically enhanced covalent interactions in Ar-tagged Au-Ag tetramers and pentamers

Abstract

Vibrational spectra of Au(n)Ag(m)(+)⋅Ar(k) (n + m = 4, 5; k = 1-4) clusters are determined by far-infrared resonant multiple photon dissociation spectroscopy in the range ν̃=100-250 cm(-1). The experimental spectra are assigned using density functional theory for geometries obtained by the Birmingham cluster genetic algorithm. Putative global minimum candidates of the Ar complexes are generated by adding Ar atoms to the Au(n)Ag(m)(+) low energy isomers and subsequent local optimization. Differential Ar binding energies indicate exceptionally strong Au-Ar bonds in Au-rich clusters, leading to fundamental changes to the IR spectra. The stronger Ar binding is attributed to a relativistically enhanced covalent character of the Au-Ar bond, while in Au-rich species charge-induced dipole interactions overcompensate the relativistic affinity to Au. Moreover, not only the absolute composition but also the topologies are essential in the description of Ar binding to a certain cluster.

Noble‐Noble Strong Union: Gold at Its Best to Make a Bond with a Noble Gas Atom

“…This is because although the Ag−Ar interaction is weak, the Au−Ar bond is quite strong and the orbital involvement is substantial to recognize it as a covalent bond. In the second contribution, the similar observation was noted in cases of larger mixed clusters, Au n Ag m + ⋅Ar k (n+m=4, 5; k=1–4). Prompted by these studies, Pan et al .…”

Relative Stability of Small Silver, Platinum, and Palladium Doped Gold Cluster Cations

“…For the Ag doped clusters, the lowest-energy isomers calculated in Reference [42] were assumed. Experimental characterization of the structures of mixed Au-Ag clusters have been performed up to size N = 5 using ion mobility experiments [43], photodissociation spectroscopy measurements [14], and far-infrared multiphoton dissociation studies [44,45]. The structures assigned in these studies agree with those in Reference [42].…”

Altering CO binding on gold cluster cations by Pd-doping

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