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

Abstract The discrete multinuclear Ag I −NHC complexes [Ag n ( 1 ) n )](X) n ; ( n =3 or 4, X=BF 4 , PF 6 ), synthesized from a bis‐NHC ligand 1 and Ag I 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 NHC ‐donor based chemistry. The existence of both the species was confirmed by various studies such as NMR ( 1 H, VT, 2D‐DOSY) and ESI‐MS analysis along with concentration studies. Importantly, replacing Ag I with other coinage metals (Au I and Cu I ) was found to alter the phenomenon entirely: a slow exchange from the tetra‐ to trinuclear species was noticed for the Au I complexes ( 4 a , b ), whereas no such process was detected in case of the Cu I complexes ( 5 a , b ).