Complexes with Atomic Gold Ions: Efficient Bis-Ligand Formation.

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Nanomaterials Science

Background:

• Atomic gold complexes are of interest due to their unique electronic and bonding properties.
• Helium nanodroplets (HNDs) provide a controlled environment for synthesizing and studying weakly bound complexes.
• Understanding ligand binding and fragmentation in metal complexes is crucial for catalysis and materials science.

Purpose of the Study:

• To synthesize and characterize gold complexes with a diverse range of ligands using HNDs.
• To investigate the preferred stoichiometry and structural motifs of gold-ligand complexes.
• To examine the influence of gold on ionization-induced intramolecular fragmentation of ligand molecules.

Main Methods:

• Helium nanodroplets (HNDs) doped with gold vapor and various ligand vapors (rare gases, diatomic, polyatomic molecules).
• Electron irradiation of doped HNDs to form cations and anions.
• High-resolution mass spectrometry for identification and abundance analysis of resulting ions (AuL_n⁺ and AuL_n^-).

Main Results:

• Formation of gold complexes with a wide array of ligands, including diatomic and polyatomic molecules.
• A strong propensity for bis-ligand formation (AuL₂⁺) with a dumbbell structure (L-Au⁺-L) was observed for most ligands.
• Gold generally enhances ionization-induced intramolecular fragmentation, except for hydrogen (H₂), where fragmentation is significantly reduced.

Conclusions:

• Helium nanodroplet isolation is an effective method for synthesizing novel gold-ligand complexes.
• The observed bis-ligand preference suggests stable covalent bonding in the L-Au⁺-L motif.
• Gold's interaction with ligands significantly alters their fragmentation behavior upon ionization, with a notable protective effect on hydrogen.