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

Abstract

Four macrocyclic hybrid salts with different numbers of benzimidazolium and amine units, [H₂L][PF₆]₂ (L = L¹, L², L³) 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 Ag₃ core is located in the cavity of one macrocyclic ligand in [Ag₃(L⁴)][PF₆]₃ (4). The photoluminescence properties of Au(I) complexes 5–8 have also been investigated.