Solvent-Induced Cluster-to-Cluster Transformation of Homoleptic Gold(I) Thiolates between Catenane and Ring-in-Ring Structures

Supramolecular ensembles adopting ring-in-ring structures are less developed compared with catenanes featuring interlocked rings. While catenanes with inter-ring closed-shell metallophilic interactions, such as d(10)-d(10) Au-I-Au-I interactions, have been well-documented, the ring-in-ring complexes featuring such metallophilic interactions remain underdeveloped. Herein is described an unprecedented ring-in-ring structure of a Au-I-thiolate Au-12 cluster formed by recrystallization of a Au-I-thiolate Au-10 [2]catenane from alkane solvents such as hexane, with use of a bulky dibutylfluorene-2-thiolate ligand. The ring-in-ring Au-I-thiolate Au-12 cluster features inter-ring Au-I-Au-I interactions and underwent cluster core change to form the thermodynamically more stable Au-10 [2]catenane structure upon dissolving in, or recrystallization from, other solvents such as CH2Cl2, CHCl3, and CH2Cl2/MeCN. The cluster-to-cluster transformation process was monitored by H-1 NMR and ESI-MS measurements. Density functional theory (DFT) calculations were performed to provide insight into the mechanism of the ring-in-ring [2]catenane interconversions.