Supramolecular assembly of molecular gold(I) compounds: An evaluation of the competition and complementarity between aurophilic (Au⋯Au) and conventional hydrogen bonding interactions

• Gold(I) compounds may associate via hydrogen bonding or aurophilic interactions.
• The propensity of hydrogen bond formation is far greater than Au⋯Au interactions.
• Steric effects are important in militating Au⋯Au interactions.
• Functional groups complexed to gold are more likely to form cyclic supramolecular synthons.

A bibliographic review of the crystallographic literature has been conducted on gold(I) compounds bearing functional groups capable of forming conventional hydrogen bonding interactions, namely, primary amide, secondary amide and carboxylic acid. The clear majority of structures featured hydrogen bonding interactions leading to well defined zero- or one-dimensional supramolecular architectures; rarely were two-dimensional architectures formed. Conversely, aurophilic, Au⋯Au, were the exception rather than the rule. This observation is correlated with steric hindrance: small atoms associated via directional hydrogen bonding compared with encumbered gold-atom environments (due to bulky ligands). Amide-{⋯HNCO}2 and carboxylic acid-{⋯HOCO}2 synthons featured in significantly more of the gold(I) structures compared with all-organic systems, particularly for non-ionic structures where charged-assisted hydrogen bonding precluded the formation of these cyclic synthons. This suggests a crystal engineering strategy of functionalising metal complexes with hydrogen bonding potential to improve opportunities of rational design of crystal structures.

Conventional hydrogen bonding interactions predominate in the supramolecular association of gold(I) compounds functionalised with groups capable of forming hydrogen bonds.Figure optionsDownload high-quality image (277 K)Download as PowerPoint slide