Self‐Assembly of Molecular Trefoil Knots Featuring Pentadecanuclear Homoleptic AuI‐, AuI/AgI‐, or AuI/CuI‐Alkynyl Coordination

Abstract

AbstractMetal‐free and metal‐containing molecular trefoil knots are fascinating ensembles that are usually covalently assembled, the latter requiring the rational design of di‐ or multidentate/multipodal ligands as connectors. In this work, we describe the self‐assembly of pentadecanuclear AuI trefoil knots [Au15(C≡CR)15] from monoalkynes HC≡CR (R=9,9‐X2‐fluorenyl with X=nBu, n‐hexyl) and [AuI(THT)Cl]. Hetero‐bimetallic counterparts [Au9M6(C≡CR)15] (M=Cu/Ag) were self‐assembled by reactions of [Au15(C≡CR)15] with [Cu(MeCN)4]+/AgNO3 and HC≡CR. The type of pentadecanuclear trefoil knots described herein is characterized by X‐ray crystallography, 2D NMR and HR‐ESI‐MS. [Au9Cu6(C≡CR)15] is relatively stable in hexane; its excited state properties were investigated. DFT calculations revealed that non‐covalent metal–metal and metal–ligand interactions, together with longer alkyl chain‐strengthened inter‐ligand dispersion interactions, govern the stability of the trefoil knot structures.