Interaction of short-chain alkane thiols and thiolates with small gold clusters: Adsorption structures and energetics

Abstract

Gold-sulfur bonding is investigated theoretically using a variety of electronic structure methods, including the Becke-Perdew semilocal density functional, the B3LYP hybrid approach, the Hartree-Fock method, and the post Hartree-Fock approaches MP2 and QCISD͑T͒. Particular emphasis is given to adsorption structure and energetics in the case of weak and strong interactions of this general type, using up to five gold atoms and up to three carbon atoms in the aliphatic chain. It is found that all methods which take into account electron correlation, including the density functional methods, lead to quite similar structures. Concerning the energetics, the Becke-Perdew functional is found to overbind typically by about 5-15%. Quasiglobal structural relaxation based on ab initio simulated annealing clearly shows that the adsorption of thiolates onto gold clusters results in a dramatic distortion of the cluster framework. From a structural point of view the thiolate sulfur-gold bond has a distinctive directional ͑covalent͒ character which results in a clear preference for Au-S-C bond angles in the range of 103.5°and 108.7°. In general, dissociation into open-shell species is preferred against the formation of the ionic closed-shell counterparts if the sulfur-gold bond is forced to break. However, neutral closed-shell products can be favored if fragmentation of the gold cluster is allowed for as a dissociation channel. Finally, it is demonstrated that using ethyl or n-propyl chains instead of the methyl group leads to only small changes of the binding energies.

Coupling of Organic and Inorganic Vibrational States and Their Thermal Transport in Nanocrystal Arrays

“…The sulfur atom of each ligand was trapped slightly above the hollow sites (2-fold, 3-fold, and 4-fold) between the surface gold atoms of the corean observation consistent with earlier experimental and computational findings. 51,52 At some positions, the sulfur atoms embedded into the core. Our approach differs from that of Luedtke and Landman, 48 where butanethiol molecules were lengthened to dodecanethiol after the attachment process.…”

Surface Dipoles and Work Functions of Alkylthiolates and Fluorinated Alkylthiolates on Au(111)

“…the bridge site is much more stable than the hollow site, which is more stable than the on-top site. In addition, calculations on small clusters indicate that DFT and Hartree-Fock (plus many-body perturbation or coupled cluster corrections) give essentially the same stable structures [50]. Calculations on the (4 2 .…”

p‐Nitrobenzoic Acid Adsorption on Nanostructured Gold Surfaces Investigated by Combined Experimental and Computational Approaches

“…[49,50] For the Au atoms, the 60-electron core was replaced by the PPs, thereby leaving the 5s 2 p 6 d 10 6s 1 valence electrons. Structural optimizations of gold clusters (based on literature reports [51] ), p-NBA in molecular and anionic form, and various initial structures of Au n -p-NBA complexes were carried out and followed by harmonic vibrational frequency calculations to confirm the nature of the obtained energy minima. Further, the anharmonic vibrational frequencies [52] were estimated for molecular and anionic forms of p-NBA using the B3LYP DFT functional and triplezeta split-valence 6-311G(d,p) basis set.…”