C3‐Symmetric Assemblies from Trigonal Polycarbene Ligands and MI Ions for the Synthesis of Three‐Dimensional Polyimidazolium Cations

Metallosupramolecular poly‐NHC‐metal assemblies were prepared from trigonal hexakis (H6‐1 a(PF6)6 and H6‐1 b(PF6)6) or nonakis (H9‐3(BF4)9) imidazolium salts and Ag2O. Complexes [Ag6(1 a)2](PF6)6 and [Ag6(1 b)2](PF6)6 are built from six Ag+ ions sandwiched between two trigonal hexacarbene ligands with an inner and an outer NHC donor in each of the three ligand arms. The metal atoms are arranged in two triangles. The hexakis‐NHC ligands bear cinnamic ester groups at the outlying NHC donors, used in postsynthetic [2+2] cycloaddition reactions linking two hexakis‐NHC ligands by three cyclobutane units to give complexes [Ag6(2 a)](PF6)6 and [Ag6(2 b)](PF6)6 bearing a dodecacarbene ligand. From the related nonakisimidazolium salt H9‐3(BF4)9, complex [Ag9(4)](BF4)9 bearing an octadecacarbene ligand was obtained. Removal of the template metals yielded very large, stable, polyimidazolium cations with 12 or 18 internal imidazolium groups. Eine trigonale Angelegenheit: Mit trigonalen Hexakis‐ und Nonakisimidazoliumsalzen wurden metallosupramolekulare Anordnungen mit 6 oder 9 MI‐Ionen (M=Ag, Au) hergestellt. Funktionalisierung der trigonalen Poly‐NHCs ermöglicht eine photochemisch induzierte [2+2]‐Cycloaddition, die die Poly‐NHCs über Cyclobutanbrücken verknüpft. Entfernung der Templat‐Metallionen ergibt Polyimidazolium‐Kationen mit 12 oder 18 Imidazoliumgruppen und potentiell großen Hohlräumen.