Synthesis and properties of cyclic tetracarbene-based organometallic assemblies

Abstract

A tubular tetranuclear silver(I) N-heterocyclic carbene (NHC) metallacage [Ag4(1)2](PF6)4 was synthesized by in situ deprotonation of a cyclic tetraimidazolium ligand with Ag2O. The interaction of obtained octacarbene-based metallacage with aromatic molecules, especially 4,4′-biphenyldicarboxaldehyde in solution was studied by NMR technique. The 4,4′-biphenyldicarboxaldehyde appearing to be located outside of the cavity with multiple C–H⋯O interactions was further confirmed by X-ray crystallography. Additionally, the reaction of the metallacage [Ag4(1)2](PF6)4 with [Cp∗IrCl2]2 afforded a dinuclear half-sandwich iridium complex [Cp∗2Ir2(1)](PF6)4 that contains two CNC-pincer-ligated Cp∗Ir fragments. The complex [Cp∗2Ir2(1)](PF6)4 was characterized by NMR spectroscopy, mass spectrometry and X-ray crystallography.