Synthesis of a Metalla[2]catenane, Metallarectangles and Polynuclear Assemblies from Di(N‐Heterocyclic Carbene) Ligands

The 2,7-fluorenone-linked bis(6-imidazo[1,5-a]pyridinium) salt H₂-1(PF₆)₂ reacts with Ag₂O in CH₃CN to yield the [2]catenane [Ag₄(1)₄](PF₆)₄. The [2]catenane rearranges in DMF to yield two metallamacrocycles [Ag₂(1)₂](PF₆)₂. 2,7-Fluorenone-bridged bis-(imidazolium) salts H₂-L(PF₆)₂ (L=2 a, 2 b) react with Ag₂O in CH₃CN to yield metallamacrocycles [Ag₂(L)₂](PF₆)₂ with interplanar distances between the fluorenone rings too small for [2]catenane formation. Intra- and intermolecular π⋅⋅⋅π interactions between the fluorenone groups were observed by X-ray crystallography. The strongly kinked 2,7-fluorenone bridged bis(5-imidazo[1,5-a]pyridinium) salt H₂-4(PF₆)₂ reacts with Ag₂O to yield [Ag₂(4)(CN)](PF₆), while the tetranuclear assembly [Ag₄(4)₂(CO₃)](PF₆)₂ was obtained in the presence of K₂CO₃.