From Au 11 to Au 13 : Tailored Synthesis of Superatomic Di-NHC/PPh 3 -Stabilized Molecular Gold Nanoclusters.

Herein, we report a new method to synthesize molecular gold nanoclusters (AuNCs) stabilized by phosphine (PR 3 ) and di-N-heterocyclic carbene (di-NHC) ligands. The interaction of di-NHC gold(I) complexes, with the general formula [(di-NHC)Au 2 Cl 2 ] with well-known [Au 11 (PPh 3 ) 8 Cl 2 ]Cl clusters provides three new classes of AuNCs through a controllable reaction sequence. The synthesis involves an initial ligand metathesis reaction to produce [Au 11 (di-NHC)(PPh 3 ) 6 Cl 2 ] + (type 1 clusters), followed by a thermally induced rearrangement/metal complex addition with the formation of Au 13 clusters [Au 13 (di-NHC) 2 (PPh 3 ) 4 Cl 4 ] + (type 2 clusters). Finally, an additional metathesis process yields [Au 13 (di-NHC) 3 (PPh 3 ) 3 Cl 3 ] 2+ (type 3 clusters). The electronic and steric properties of the employed di-NHC ligand affect the product distribution, leading to the isolation and full characterization of different clusters as the main product. A type 3 cluster has been also structurally characterized and was preliminarily found to be strongly emissive in solution.