Macrocyclic dinuclear gold(I) and silver(I) NHCs complexes

The ligands bis-(imidazolium) hexafluorophosphate [RHimyCH2OCH2HimyR][PF6-]2 (Himy = –C3N2H3–, imidazolium; R = 1-naphthylmethylene, 1a; 9-anthracenylmethylene, 1b) with an oxoether chain were easily prepared by the reaction of substituted imidazole with the diglycol diiodide, followed by exchange of anions with PF6-. 1a and 1b reacted with Ag2O in DMSO or CH3CN to yield [2 + 2] dinuclear Ag(I) NHCs macrocyclic complexes 2a and 2b, which showed much different conformation in solid corresponding to the R- substituent. Carbene transmetalation reactions of 2a–b with Au(SMe2)Cl give dinuclear Au(I) analogs 3a and 3b. The new NHCs complexes were characterized by elemental analyses, 1H NMR, 13C NMR and the structures of 2a–b and 3a were confirmed by X-ray diffraction determination.

Graphical abstractThe new dinuclear silver(I) and gold(I) macrocyclic complexes bridged by high-flexible bidentate NHC ligands have been prepared. The new complexes can adopt a cross or a parallel configuration depending on the intramolecular weak M⋯M interaction or intermolecular π–π stacking between substituents on the imidazole ring.Figure optionsDownload full-size imageDownload as PowerPoint slide