Synthesis and Characterization of Poly-NHC-Derived Silver(I) Assemblies and Their Transformation into Poly-Imidazolium Macrocycles

Three metallosupramolecular assemblies composed of two bis-NHCs and two silver atoms, [4](PF6)(2), two tetra-NHCs and four silver atoms, [7](PF6)(4), and two tri-NHCs and three silver atoms [8](BF4)(3), have been prepared. Assemblies [4](PF6)(2) and [7](PF6)(4) feature NHC ligands decorated with terminal olefin groups. Irradiation of [4](PF6)(2) yielded complex [5](PF6)(2) with two terminal cyclobutane rings linking the two bis-NHC ligands. Liberation of the macrocyclic tetrakisimidazolium salt H-4-6(PF6)(4) was achieved by reaction of [5](PF6)(2) with NH4Cl/NH4PF6. No [2+2] cycloaddition was observed upon irradiation of [7](PF6)(4), apparently due to an unfavorable orientation of the olefin groups. Irradiation of complex [8](BF4)(3) with three internal pairs of olefin groups leads to [9](BF4)(3) as a mixture of two isomers that differ on the relative orientation of the internal cyclobutane rings. Reaction of [9](BF4)(3) with NH4Cl/NH4BF4 yields an isomer mixture of the novel cage-line hexakisimidazolium salt H-6-10(BF4)(6).

Automated summary

Three metallosupramolecular assemblies consisting of NHC ligands and silver atoms have been prepared. Each assembly shows different structures and reactivities, including the formation of cyclobutane rings and the generation of different isomers.