Synthesis of ruthenium–bis(silyl) chelate complexes without carbonyl ligands by reactions of a bis(allyl)ruthenium(II) complex with bis(hydrosilyl)xanthene and phosphines

• Published in: Journal of organometallic chemistry 2020-07, Vol.919, p.121316, Article 121316
• Main Authors: Kitano, Takeo, Komuro, Takashi, Sato, Keita, Tobita, Hiromi
• Format: Article
• Language: English
• Subjects: Chelate ligand; Phosphine; Ruthenium; Silyl complex; Xanthene
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2020.121316

Ruthenium complexes bearing a xanthene-based bis(silyl) chelate ligand without CO ligands, Ru(κ3Si,O,Si-xantsil)(H)[PCy2(η3-C6H8)] (1) and Ru(κ2Si,Si-xantsil)(η6-toluene)(L) (L = cyclooctene (coe) (2) and PPh3 (3)), were synthesized by reactions of Ru(η3-2-methylallyl)2(cod) (A, cod = 1,5-cyclooctadiene) with 4,5-bis(dimethylsilyl)-9,9-dimethylxanthene (xantsilH2) in the presence of phosphines PR3 (R = cyclohexyl (Cy), cyclopentyl (Cyp), and Ph) in cyclohexane or toluene at 60 °C. Complexes 1–3 were fully characterized by X-ray crystallography and NMR spectroscopy. In the case of the reaction with PCy3, complex 1 bearing a phosphine–η3-cyclohexenyl chelate ligand was formed via activation of three sp3-C–H bonds on a cyclohexyl group and hydrogenation of 1,5-cyclooctadiene to cyclooctene. Complex 3 was found to undergo exchange of the η6-toluene ligand with benzene at room temperature. Reaction of a bis(allyl)ruthenium(II) complex with bis(hydrosilyl)xanthene in the presence of tricyclohexylphosphine in cyclohexane at 60 °C afforded bis(silyl)ruthenium chelate complexes containing a phosphine–η3-cyclohexenyl ligand, whereas the corresponding reaction by use of tricyclopentylphosphine or triphenylphosphine in toluene gave a bis(silyl)(η6-toluene) complex with an η2-cyclooctene or a PPh3 ligand, respectively. [Display omitted] •Bis(silyl)xanthene chelate Ru complexes were synthesized from a bis(allyl) complex.•All the bis(silyl) complexes were characterized by X-ray and NMR analysis.•Possible formation mechanisms for the bis(silyl) complexes were proposed.•Arene exchange of an (η6-toluene)bis(silyl) complex was observed at room temperature.