Synthesis and characterization of oligomeric and polymeric silver-imidazol-2-ylidene iodide complexes

Reaction of N,N′-dimethylimidazolium iodide with Ag2O in CH2Cl2 leads to the coordination polymer [Ag(carbene)2]2[Ag4I6] (2), which consists of the cation [Ag(carbene)2]+ and anionic infinite one-dimensional [Ag4I6]2− chain. The cations and anionic chains are connected into two-dimensional network structure. Treatment of N-allyl-N′-methylimidazolium iodide with Ag2O yielded a tetranuclear N-heterocyclic carbene silver complex [Ag(carbene)2]2[Ag2I4] (3). The polymeric [Ag(carbene)][AgI2] (4) was isolated when the tetranuclear complex 3 was heated at 80 °C. The monocarbene complex 4 adopts infinite one-dimensional ribbon stair structure in which the silver atoms are held together by multiple iodide bridges and weak Ag⋯Ag interaction. The compounds have been fully characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography.