Strengthening gold–gold bonds by complexing gold clusters with noble gases

Abstract

We report an unexpectedly strong and complex chemical bonding of rare-gas atoms to neutral gold clusters. The bonding features are consistently reproduced at different levels of approximation within density-functional theory and beyond: from GGA, through hybrid and double-hybrid functionals, up to renormalized secondorder perturbation theory. The main finding is that the adsorption of Ar, Kr, and Xe reduces electron-electron repulsion within gold dimer, causing strengthening of the Au\Au bond. Differently from the dimer, the rare-gas adsorption effects on the gold trimer's geometry and vibrational frequencies are mainly due to electron occupation of the trimer's lowest unoccupied molecular orbital. For the trimer, the theoretical results are also consistent with far-infrared multiple photon dissociation experiments.Binding of rare-gas (RG) atoms to molecules and metal clusters has been studied intensively in the past years [1][2][3][4][5][6][7][8]. Due to their very stable closed-shell electronic configuration, when interacting with neutral species and clusters, RG atoms are expected to interact via dispersion forces and polarization by multipole moments of the clusters.However, a closer look to the binding of RG atoms to Au clusters reveals a much more complex nature of the interaction [3,6,7]. In most of the previous studies, electrostatic effects are expected to play a major role in the interaction between the RG atom(s) and Au, since the Au atom is either charged or is a part of a polar molecule (with a large dipole moment). Reports on theoretical analysis of the binding of RG atoms to bare neutral Au M clusters are very scarce [10].We find that the present understanding of RG-Au M interaction is not conclusive due to the sensitivity of RG-Au M electronic structure to the level of theory. Therefore, in this work we analyze bonding between RG atoms (Ne, Ar, Kr, and Xe) and the smallest Au M clusters (M = 2, 3) using a variety of different theoretical approaches. In fact, we believe that interaction of this type has been overlooked so far, at least for this class of system. Our analysis explains several puzzling features of the observed spectra obtained with far-IR resonance-enhanced multiple photon dissociation (FIR-MPD) spectroscopy, which are reported in detail in Ref. [9].In Fig. 1 we show, in the upper half of each panel, the FIR-MPD spectra of Au 3 complexed with one or two Kr atoms, at T = 100 K. The first striking aspect of the measured spectra is that the adsorption of the second Kr changes the spectrum significantly. This fact suggests that the interaction of Kr with Au 3 cannot be treated as a perturbation.To explain these findings, we have calculated the geometry, electronic structure, and vibrational frequencies of RG-Au complexes. The calculations were performed with FHI-aims [11] program package for an accurate all-electron description based on numeric atom-centered basis functions. The IR spectra at finite temperature were calculated by performing Born-Oppenheimer molecular dynamics simulations ...

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

“…At the CCSD(T)/aug‐cc‐pVQZ level, the Ne−Au bond strength was recorded as 2.1 kcal/mol. In a relevant work on Ng interaction with neutral cluster, Ghiringhelli and Levchenko observed an interesting phenomenon. Through their experimental and theoretical studies, they found that the absorption of Ng (Ar−Xe) reduces the electron‐electron repulsion in Au 2 and, hence, it strengthens this bond.…”

The Nature of Bonding between Argon and Mixed Gold–Silver Trimers

“…[29] But for the closed-shell gold dimer Au 2 ,as trengthening of the AuÀAu bond is observed upon absorbing Kr, resulting in significantly influenced IR spectra, pointing to an increased covalent character. [30] On this basis,the goal of this study is to shed light on the Au + À Ng closed-shell interaction with the help of Ar complexes of mixed AuÀAg trimer cations by means of experimental IR spectra and DFT calculations.…”

Excimer‐ und Exciplex‐Bildung in durch aurophile Wechselwirkungen präkonditionierten Gold(I)‐ Komplexen

“…In diesen linearen Molekülen ( C ∞v , D ∞h Symmetrie) wurde eine geringfügige Verkürzung der Au‐Au‐Abstände von 2.429 (für Au 2 ) auf 2.421 und 2.40 Å (für Au 2 ⋅Kr bzw. Au 2 ⋅Kr 2 ) berechnet (MP2‐Rechnungen) …”

“…Für Au 2 gibt es offensichtlich einen deutlichen Unterschied zwischen diesen berechneten und dem experimentellen Wert von 2.4715 Å (siehe oben). In älteren und jüngeren theoretischen Untersuchungen von Au 2 werden Daten um die 2.50 Å (MP2) und wieder solche am kürzeren Ende (MP2: 2.429 Å) erhalten . Diese Diskrepanz ist momentan noch unerklärt.…”