Supramolecular Coordination Cages Based on N‐Heterocyclic Carbene‐Gold(I) Ligands and Their Precursors: Self‐Assembly, Structural Transformation and Guest‐Binding Properties

The incorporation of functional groups into the cavity of discrete supramolecular coordination cages (SCCs) will bring unique functions and applications. Here, three dicarboxylate ligands (H 2 L1 Cl, H 2 L2 Cl and H 2 L3 Cl) containing N‐heterocyclic carbene (NHC) precursors as linkers were introduced to construct SCCs by combining with two C 3 ‐symmertic (CpZr) 3 ( μ 3 ‐O)( μ 2 ‐OH) 3 clusters as three‐connect vertices, resulted in a series of rugby‐like V 2 E 3 (V=vertex, E=edge) type homoleptic cages ( SCC‐1 , SCC‐2 and SCC‐3 ). However, V 4 E 6 ‐type tetrahedral cages ( SCC‐4 and SCC‐5 ), incorporating six Au‐NHC moieties, were obtained when the corresponding NHC‐gold(I) functionalized ligands (H 2 L1 Au , H 2 L2 Au ) were applied. For the first time, we present a trackable CpZr‐involved cage to cage conversion to generate a heteroleptic V 2 E 3 cage ( SCC‐6 ) from two homoleptic cages ( SCC‐2 and SCC‐5 ) with different geometries of V 2 E 3 and V 4 E 6 . The heteroleptic assembly SCC‐6 can also be formed upon a subcomponent displacement strategy. The structural transformation and reassembly processes were detected and monitored by 1 H NMR spectroscopy and electrospray‐ionization mass spectrometry. The formation of heteroleptic assembly was further supported by single crystal X‐ray diffraction analysis. Moreover, homoleptic cage SCC‐2 possesses a trigonal bipyramidal cationic cavity allowing the encapsulation of a series of sulfonate anionic guests.