Goldπ aryl interactions as supramolecular synthons

Auπ interactions whereby the electron-rich π-system of C₆-aromatic rings interact with gold are shown to exist in the crystal structures of both gold(I) and gold(III) complexes, and have been revealed to occur between neutral/neutral, cationic/cationic, and cationic/anionic systems. Supramolecular aggregation facilitated by Auπ interactions leads to the formation of 0-dimensional aggregates, e.g. arising from an interaction between a gold complex and a solvent molecule, loosely associated spherical aggregates, e.g. cooperative interactions between centrosymmetrically related gold complexes, and even extended supramolecular polymeric chains of variable topology (e.g. linear, step ladder, and helical). The described Auπ interactions represent a new synthon in structural gold chemistry that should be considered in any complete analysis of their crystal structures.