N-Heterocyclic carbene derivatives to modify gold superatom characteristics. Tailorable electronic and optical properties of [Au₁₁(PPh₃)₇LCl₂]⁺ as a cluster from relativistic DFT

Abstract

Atomically-precise gold superatoms are useful building blocks prone to be tunable properties by the proper choice of ligands within the protecting ligand layer. Herein, different N-heterocyclic carbene (NHC) derivatives from...

N-Heterocyclic Carbene-Stabilized Atomically Precise Metal Nanoclusters

“…A theoretical study performed by Muñoz-Castro examined the effect ligands have on the electronic and optical properties by varying the electron donating and accepting ability of NHC ligands on a mixed-ligand Au 11 cluster while keeping steric effects consistent (Figure ). The NHCs employed have donating abilities in the following order 79 > 80 > 81 > 82 > 83 according to their respective Tolman electronic parameters. Isopropyl groups are used as substituents in all cases to focus on electronic effects.…”

“…It was determined that as the electron donating ability of the ligand decreased, the HOMO–LUMO gap of the nanocluster decreased even with only a single NHC on the cluster. The observation of significant changes in the HOMO–LUMO gap for different clusters implies that the NHC ligand affects the frontier orbitals of the cluster …”

“…103,104 A theoretical study performed by Munõz-Castro examined the effect ligands have on the electronic and optical properties by varying the electron donating and accepting ability of NHC ligands on a mixed-ligand Au 11 cluster while keeping steric effects consistent (Figure 30). 105 The NHCs employed have Isopropyl groups are used as substituents in all cases to focus on electronic effects. It was determined that as the electron donating ability of the ligand decreased, the HOMO−LUMO gap of the nanocluster decreased even with only a single NHC on the cluster.…”

“…The observation of significant changes in the HOMO−LUMO gap for different clusters implies that the NHC ligand affects the frontier orbitals of the cluster. 105 Prolate gold nanoclusters are characterized by more pronounced visible bands observed at lower energies typically attributed to Au−Au core (HOMO−LUMO) transitions. For example, prolate Au 10 cluster 58, with a unique elongated core, has a pronounced visible band at 546 nm (Figure 31A), while toroidal Au 10 cluster 30 exhibits two relatively weak bands at 469 and 498 nm (Figure 31B).…”

“…Figure 30. [Au 11 (PPh 3 ) 7 (L)Cl 2 ] + (19, 79−83) clusters with various NHC ligands used for ligand exchange computational study 105. Color legend: yellow, Au; gray, C; green, Cl; orange, P.…”