Self-Assembly of Benzimidazole-Derived Tris-NHC Ligands and AgI -Ions to Hexanuclear Organometallic Cages and Their Unusual Transmetalation Chemistry.

Abstract

Multi-ligand self-assembly to attain the AgI -N-heterocyclic carbene (NHC)-built hexanuclear organometallic cages of composition [Ag6 (3 a,b)4 ](PF6 )6 from the reaction of benzimidazole-derived tris(azolium) salts [H3 -3 a,b](PF6 )3 with Ag2 O was achieved. The molecular structures of the cages were established by X-ray diffraction studies along with NMR and MS analyses. The existence of a single assembly in solution was supported by diffusion-ordered spectroscopy (DOSY) 1 H NMR spectra. Further, transmetalation reactions of these self-assembled complexes, [Ag6 (3 a,b)4 ](PF6 )6 , with CuI /AuI -ions provided various coinage metal-NHC complexes having diverse molecular compositions, which included the first example of a hexanuclear CuI -dodecacarbene complex, [Cu6 (3 b)4 ](PF6 )6 .