Stereodirected Construction of Lemniscular Metallacycles via Linear d10AgI/AuI–NHC Coordination Engineering

Comprehensive Summary Helically twisted molecular architectures are critical motifs in both biology and synthetic supramolecular chemistry, with unique functional properties derived from their chiral geometries. Although lemniscular (figure‐eight) macrocycles with a noncontact crossover point have attracted increasing interest, their metallosupramolecular analogs remain underexplored, largely because of synthetic challenges that hinder precise control. Herein, we report a coordination‐driven strategy for the controlled construction of lemniscular metallacycles by exploiting the linear coordination geometry of Ag I and Au I complexes containing N ‐heterocyclic carbene (NHC) ligands. The key to this approach is the design of a bis‐NHC imidazolium ligand containing helicene moieties, which promotes homochiral helicene dimerization and suppresses noncrossover macrocycle formation. Ag I and Au I –NHC lemniscular architectures were synthesized via this method, and the Au I complex was validated through multiple synthetic pathways. The generated structures were characterized via electrospray ionization mass spectrometry, ultraviolet–visible absorption and fluorescence emission spectroscopy, X‐ray crystallography, and density functional theory calculations, confirming the formation of the target metallacycles. Notably, this work addresses the long‐standing scarcity of metallosupramolecular lemniscular systems, increases the structural diversity of macrocycles, and establishes a platform for the systematic investigation of the emergent functionalities of these complexes.