Au_n (n = 1,11) Clusters Interacting With Lone-Pair Ligands

Abstract

We analyze the pattern of binding energies (BEs) of small Aun clusters (n = 1-7, 11) with lone-pair ligands (L = H2O, SH2, NH3, PH3, PF3, PCl3, and PMe3) employing the density functional theory. We use PBE0 functional with the dispersion correction and scalar relativistic effective core potential. This approach provides correct BEs when compared with benchmark CCSD(T) calculations for Au-L and Au2-L complexes. The pattern of BEs of Aun-L complexes is irregular with BE for Au3 ≈ Au4 > Au2 > Au7 > Au5 > Au11 > Au6 > Au1. Electron affinities (EAs) of Aun clusters exhibit oscillatory pattern with the cluster size. Binding energies of Aun-L complexes are oscillatory as well following EAs of Aun clusters. BEs of odd and even Aun-L complexes were analyzed separately. The bonding mechanism in odd Aun-L complexes is dominated by the lone pair → metal electron donation to the singly occupied valence Aun orbital accompanied by the back-donation. Even Aun clusters create covalent Aun-L bonds with BEs higher than those in odd Aun-L complexes. The BEs pattern and optimized geometries of Aun-L complexes correspond to the picture of creating the gold-ligand bond through the lone pair of a ligand interacting with the singly occupied molecular orbital in odd clusters or lowest unoccupied molecular orbital in even clusters of Aun. Ligands in both odd and even Aun-L complexes form three groups with binding energies that correlate with their ionization energies. The lowest BE is calculated for H2O as a ligand, followed by SH2 and NH3. PX3 ligands exhibit highest BEs.

Analysis of the conformational properties of amine ligands at the gold/water interface with QM, MM and QM/MM simulations

“…In Table 1, comparison is made with additional density functionals, including M06, 49 a double-hybrid functional (B2PLYP 50 ), a range-separation functional (CAM-B3LYP 51 ) and a meta-GGA functional (TPSSh 52,53 ); some of them were found to be reliable for gold-ligand interactions in previous benchmark calculations for smaller systems. 28,29 Results here suggest that PBE and PBE-GD3 are the most reliable for the systems of interest here. Moreover, with these two functionals, using a substantially smaller basis set (Lanl2dz for Au and 6-31G(d) for main group elements) does not lead to much larger errors.…”

“…below); previous benchmark studies28,29 that focused on smaller Au-ligand systems found that PBE-GD3 and TPSSh are among the best functionals compared to CCSD(T) calcu-…”

Gold nanoclusters as prospective carriers and detectors of pramipexole

“…This charge-flow tendency, from organic molecules to metallic surfaces, is also consistent with previous reports. 67,68 The nature of Au–PPX bond is basically analogous to that of gold clusters interacting with lone-pair ligands 69 and mostly dominated by a σ bond with the distribution of unshared electrons in the HOMO of PPX molecule and the LUMO of gold clusters. As illustrated in Fig.…”

Theoretical Study of the Binding of the Thiol-Containing Cysteine Amino Acid to the Silver Surface Using a Cluster Model

“…For the interaction of Ag 2 with cysteine in the gas phase, its contribution to the final binding energy is computed to be ∼1.5 kcal/mol, which lies within the expected uncertainty of up-to-date DFT calculations, being ±3.0 kcal/mol. The previous investigation 40 on the lone-pair affinity of small gold clusters also confirmed that the BSSE uncorrected results tend to correlate with the benchmark data better than the corrected ones because of error mutual cancellations. To include the influences of the biological environment, we employ the integral equation formalism-polarizable continuum model (IEF-PCM) 41 for treating the systems considered in aqueous solution.…”