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 H 2 -1(PF 6 ) 2 reacts with Ag 2 O in CH 3 CN to yield the [2]catenane [Ag 4 (1) 4 ](PF 6 ) 4 . The [2]catenane rearranges in DMF to yield two metallamacrocycles [Ag 2 (1) 2 ](PF 6 ) 2 . 2,7-Fluorenone-bridged bis-(imidazolium) salts H 2 -L(PF 6 ) 2 (L=2 a, 2 b) react with Ag 2 O in CH 3 CN to yield metallamacrocycles [Ag 2 (L) 2 ](PF 6 ) 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 H 2 -4(PF 6 ) 2 reacts with Ag 2 O to yield [Ag 2 (4)(CN)](PF 6 ), while the tetranuclear assembly [Ag 4 (4) 2 (CO 3 )](PF 6 ) 2 was obtained in the presence of K 2 CO 3 .