Synthesis, structure and catalytic activity of the first iridium(I) siloxide versus chloride complexes with 1,3-mesitylimidazolin-2-ylidene ligand

The first iridium(I) complex containing siloxyl and N-heterocyclic carbene ligand such as [Ir(cod)(IMes)(OSiMe3)] (1) and [Ir(CO)2(IMes)(OSiMe3)] (3) have been synthesized and their structures solved by spectroscopy and X-ray methods as well as catalytic properties in selected hydrogenation reactions have been presented in comparison to their chloride analogues, i.e. [Ir(Cl)(cod)(IMes)] (2) and [Ir(Cl)(CO)2(IMes)] (4). The attempts at synthesis of iridium(I) complex with tert-butoxyl ligand has failed as leading instead to the iridium hydroxide complex [Ir(cod)(OH)(IMes)] (5) whose X-ray structure has also been solved. All complexes (1)–(5) show square planar geometry typical of the four-coordinated iridium complexes. Catalytic activity of complexes 1 and 2 was tested in transfer hydrogenation of acetophenone and hydrogenation of olefins.

Graphical abstractThe first iridium(I) complexes containing siloxyl and N-heterocyclic carbene ligand, i.e. [Ir(cod)(IMes)-OSiMe3] (1) and [Ir(CO)2-(IMes)(O-SiMe3)] (3), have been synthesized and their structures solved by spectroscopy and X-ray methods as well as catalytic properties in transfer hydrogenation and hydrogenation have been presented.Figure optionsDownload full-size imageDownload as PowerPoint slide