Synthesis and characterization of Ag(I) and Au(I) complexes with macrocyclic hybrid amine N-heterocyclic carbene ligands

Four macrocyclic hybrid salts with different numbers of benzimidazolium and amine units, [H2L][PF6](2) (L = L-1, L-2, L-3) and [H4L4][PF6](4), have been employed as the heterocyclic carbene (NHC) precursors toward new Ag(i)- and Au(i)-NHC complexes. Three trinuclear and one tetranuclear Ag(i) complexes 1-4 have been obtained from the reactions of the NHC precursors and Ag2O in acetonitrile. Four dinuclear Au(i)-NHC complexes 5-8 have been prepared by reacting the NHC precursors and AuCl(SMe2) in the presence of NaOAc in DMF. The molecular structures of all the complexes are established by single-crystal X-ray diffraction studies. The metal ions in the Ag(i) complexes 1-3 and the Au(i) complexes 5-7 are coordinated with two macrocyclic NHC ligands to form a sandwiched structure. In contrast, a trinuclear Ag-3 core is located in the cavity of one macrocyclic ligand in [Ag-3(L-4)][PF6](3) (4). The photoluminescence properties of Au(i) complexes 5-8 have also been investigated.