Synthesis, structural and spectroscopic studies of ruthenium-indolizinone complexes

Abstract

The first examples of structurally characterized ruthenium–indolizinone zwitterions complexes, namely [Ru([14]aneS4)(Cl)(indolizinone)](ClO4) (1), [Ru([14]aneS4)(CH3CN)(indolizinone)](ClO4)2 (1’) as well as [Ru([9]aneS3)(N^N)(indolizinone)](ClO4)2 (2), were isolated from reactions between Ru(II) precursors and pyridyine-substituted alkynyl ketones (abbreviated as pyridyl ynones) in THF or MeOH. All these complexes were obtained in high yield (64 – 94%). The molecular structure of 2 was determined by X-ray crystallography. Spectroscopic studies of these complexes were also performed. The experimental results suggest that the interaction between pyridyl-ynones and Ru(II) complexes support 5-endo-dig cyclization pathway and discount a Ru–vinylidene intermidacy to give metalated–indolizinones.