Alkylruthenium Complexes Containing Polypyridyl Ligands: Synthesis, Characterization, and Immobilization on Silica

• Published in: European journal of inorganic chemistry 2013-06, Vol.2013 (16), p.2893-2899
• Main Authors: Huang, Enrique Kwan, Cheung, Wai-Man, Chan, Ka-Wang, Lam, Frank Leung-Yuk, Hu, Xijun, Zhang, Qian-Feng, Williams, Ian D., Leung, Wa-Hung
• Format: Article
• Language: English
• Subjects: Alkylation; Benzyl alcohol; Catalysis; Catalysts; Electronics; Electrons; Grafting; Heterogeneous catalysis; Immobilization; Oxidation; Reflectance; Ruthenium; Silicon dioxide; Spectrum analysis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201300043

The treatment of [Ru(CO)2Cl2]x with 4,4′,4″‐tri‐tert‐butyl‐2,2′:6′,6″‐terpyridyl (tbtpy) in tetrahydrofuran at reflux afforded trans‐[Ru(tbtpy)Cl2(CO)] (1). The alkylation of complex 1 with excess Me3SiCH2MgCl afforded a mixture of trans‐[Ru(tbtpy)(CH2SiMe3)2(CO)] (2) and trans‐[Ru(tbtpy)(CH2SiMe3)Cl(CO)] (3), whereas complex 3 could be obtained in good yield by the alkylation of complex 1 with 1 equiv. of Me3SiCH2MgCl. On the other hand, the alkylation of 1 with MeLi and PhCH2MgBr afforded the monoalkyl complexes [Ru(tbtpy)(Me)Cl(CO)] (4) and [Ru(tbtpy)(CH2Ph)Cl0.5Br0.5(CO)] (5), respectively. The crystal structure of complex 5 was determined. Complex 2 and the previously prepared mer‐[Ru(dtbpy)(CH2SiMe3)3(NO)] (dtbpy = 4,4′‐di‐tert‐butyl‐2,2′‐bipyridyl) were immobilized on SBA‐15 by treating the Ru complexes with SBA‐15 in benzene at room temperature. 1H NMR spectroscopy indicated that the reaction of complex 2 and [Ru(dtbpy)(CH2SiMe3)3(NO)] with SBA‐15 in C6D6 resulted in the formation of approximately 1 equiv. of SiMe4, which suggests the grafted species are possibly (≡SiO)Ru(tbtpy)(CH2SiMe3)(CO) and (≡SiO)Ru(dtbpy)(CH2SiMe3)2(NO), respectively. The Ru‐grafted SBA‐15 materials were characterized by IR, reflectance UV/Vis, and X‐ray photoelectron spectroscopy as well as transmission electronic microscopy, and their catalytic performance in the oxidation of benzyl alcohol with tert‐butyl hydroperoxide was examined. The alkylation of [Ru(tbtpy)(CO)Cl2] (tbtpy = 4,4′,4″‐tri‐tert‐butyl‐2,2′:6′,6″‐terpyridyl) with Me3SiCH2MgCl afforded a mixture of trans‐[Ru(tbtpy)(CH2SiMe3)2(CO)] and trans‐[Ru(tbtpy)(CH2SiMe3)Cl(CO)]. trans‐[Ru(tbtpy)(CH2SiMe3)2(CO)] and mer‐[Ru(dtbpy)(CH2SiMe3)3(NO)] were immobilized on SBA‐15 by elimination of SiMe4 and the grafted species showed catalytic behavior.