Syntheses and structural characterization of tetranuclear organometallic macrocycles based on bent connector

Abstract

4-Amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4-abpt) as bent bridging ligand has been utilized to construct half-sandwich tetranuclear organometallic complexes, namely [Cp*4M4(C2O4)2(4-abpt)2](OTf)4 (M = Rh(1); Ir(2)) and [Cp*4M4(bibzIm)2(4-abpt)2](OTf)4 (M = Rh(3); Ir(4)). Single-crystal X-ray diffraction structural analysis combined with 1H NMR spectra reveal that complexes 1–4 show rectangular macrocycles, in which half-sandwich binuclear units are interlinked by 4-abpt ligands that have relatively flexible angle changes. For macrocycles 1–3, they all feature an anti-arrangement of 4-abpt ligands; However, 4-abpt ligands adopt a syn-arrangement in macrocycle 4.