Reactivity studies of cyclopentadienyl ruthenium(II), osmium(II) and pentamethylcyclopentadienyl iridium(III) complexes towards 2-(2′-pyridyl)imidazole derivatives

The reaction of [CpRu(PPh3)2Cl] and [CpOs(PPh3)2Br] with chelating 2-(2′-pyridyl)imidazole (N ∩ N) ligands and NH4PF6 yields cationic complexes of the type [CpM(N ∩ N)(PPh3)]+ (1: M = Ru, N ∩ N = 2-(2′-pyridyl)imidazole; 2: M = Ru, N ∩ N = 2-(2′-pyridyl)benzimidazole; 3: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-dimethylimidazole; 4: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-diphenylimidazole; 5: M = Os, N ∩ N = 2-(2′-pyridyl)imidazole; 6: M = Os, N ∩ N = 2-(2′-pyridyl)benzimidazole). They have been isolated and characterized as their hexafluorophosphate salts. Similarly, in the presence of NH4PF6, [Cp∗Ir(μ-Cl)Cl]2 reacts in dry methanol with N ∩ N chelating ligands to afford in excellent yield [Cp∗Ir(N ∩ N)Cl]PF6 (7: N ∩ N = 2-(2′-pyridyl)imidazole; 8: N ∩ N = 2-(2′-pyridyl)benzimidazole). All the compounds have been characterized by infrared and NMR spectroscopy and the molecular structure of [1]PF6, [2]PF6 and [7]PF6 by single-crystal X-ray structure analysis.

Graphical abstractThe reactions of [CpRu(PPh3)2Cl], [CpOs(PPh3)2Br] and [Cp∗Ir(μ-Cl)Cl]2 with chelating 2-(2′-pyridyl)imidazole (N ∩ N) ligands and NH4PF6 yields cationic complexes of the type [CpM(N ∩ N)(PPh3)]PF6 and [Cp∗Ir(N ∩ N)Cl]PF6, respectively in good yield. These complexes were characterized with spectral and single-crystal X-ray study.Figure optionsDownload full-size imageDownload as PowerPoint slide