Self-Assembly of a Bis-NHC Ligand and Coinage Metal Ions: Unprecedented Metal-Driven Chemistry between the Tri- and Tetranuclear Species.

The discrete multinuclear Ag -NHC complexes [Ag (1) )](X) ; (n=3 or 4, X=BF , PF ), synthesized from a bis-NHC ligand 1 and Ag ions via multiligand self-assembly, were observed to be in equilibrium between two forms (tri- and tetranuclear) in solution on the NMR timescale, which is unprecedented in C -donor based chemistry. The existence of both the species was confirmed by various studies such as NMR ( H, VT, 2D-DOSY) and ESI-MS analysis along with concentration studies. Importantly, replacing Ag with other coinage metals (Au and Cu ) was found to alter the phenomenon entirely: a slow exchange from the tetra- to trinuclear species was noticed for the Au complexes (4 a, b), whereas no such process was detected in case of the Cu complexes (5 a, b).

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

Multi-ligand self-assembly to attain the Ag -N-heterocyclic carbene (NHC)-built hexanuclear organometallic cages of composition [Ag (3 a,b) ](PF ) from the reaction of benzimidazole-derived tris(azolium) salts [H -3 a,b](PF ) with Ag 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) H NMR spectra.