Synthesis and crystal structures of twisted three-dimensional assemblies of adamantane-bridged tris-NHC ligands and AgI

Abstract

Two adamantane-bridged tripodal trisimidazolium or trisbenzimidazolium salts were designed as C_3v-symmetrical tricarbene ligands and synthesized in good yields. The reaction of the tripodal trisazolium salt precursors with silver oxide provided trisilver hexacarbene complexes bearing a three-dimensional framework. Multinuclear NMR spectroscopy and mass spectrometry data showed that the complexes were symmetric structures of two tricarbene ligands, three metal ions, and three counter anions. X-ray crystallographic analyses revealed that both complex cations adopted a highly twisted conformation. The complex cations built from the trisimidazolium salts were arranged into columnar structures through CH/π interactions, which were assembled into a three-dimensional network structure by intermolecular CH/F interactions via hexafluorophosphate anions. The complex cations generated from the trisbenzimidazolium salts were aligned into columnar structures, which were arranged into a network structure through CH/π interactions. Solvents and counter anions were accommodated in the spaces of the crystalline lattices.