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

The reaction of [CpRu(PPh3)(2)Cl] and [CpOs(PPh3)(2)Br] with chelating 2-(2'-pyridyl)imidazole (N boolean AND N) ligands and NH4PF6 yields cationic complexes of the type [CpM(N boolean AND N)(PPh3)](+) (1: M=Ru, N boolean AND N=2-(2'-pyridyl)imidazole; 2: M=Ru, N boolean AND N=2-(2'-pyridyl)benzimidazole; 3: M=Ru, N boolean AND N=2-(2'-pyridyl)-4,5-dimethylimidazole; 4: M=Ru, N boolean AND N=2-(2'-pyridyl)-4,5-diphenylimidazole; 5: M=Os, N boolean AND N=2-(2'-pyridyl)imidazole; 6: M=Os, N boolean AND N=2-(2'-pyridyl)benzimidazole). They have been isolated and characterized as their hexafluorophosphate salts. Similarly, in the presence of NH4PF6, [Cp*Ir(mu-Cl)Cl](2) reacts in dry methanol with N boolean AND N chelating ligands to afford in excellent yield [Cp*Ir(N boolean AND N)Cl]PF6 (7: N boolean AND N=2-(2'-pyridyl)imidazole; 8: N boolean AND 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. (c) 2007 Elsevier Ltd. All rights reserved.