Ruthenium Carbene鈥揇iether Ligand Complexes: Catalysts for Hydrogenation of Olefins
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- 作者：Tongen Wang ; Conor Pranckevicius ; Clinton L. Lund ; Michael J. Sgro ; Douglas W. Stephan
- 刊名：Organometallics
- 出版年：2013
- 出版时间：April 8, 2013
- 年：2013
- 卷：32
- 期：7
- 页码：2168-2177
- 全文大小：388K
- 年卷期：v.32,no.7(April 8, 2013)
- ISSN：1520-6041
文摘
A series of carbene鈥揹iether ligands were prepared and the corresponding Ag salts used to prepare the complexes RuHCl(PPh3)2(Im(OR)2) (Im(OR)2 = C3H2(NCH2CH2OR)2; R = Me (4a), t-Bu (4b), tert-hexyl (4c), Ph (4d), 2,6-i-Pr2C6H3 (4e)). In an analogous fashion the species RuHCl(PPh3)2(Y2Im(OMe)2) (Y2Im(OMe)2 = Y2C3(NCH2CH2OMe)2; Y2 = C6H4 (4f), Y = Cl (4g), Me (4h)) were also synthesized. Similarly RuHCl(CO)(PPh3)2(Im(OMe)2) (5) was prepared and readily converted to RuHCl(CO)(SIMes)(Im(OMe)2) (6) via treatment with SIMes. The reaction of 4a with SIMes afforded RuHCl(SIMes)(Im(OMe)2)(PPh3) (7), which reacts subsequently with Na[BPh4] to give [RuH(Im(OMe)2)(SIMes)][(畏6-Ph)BPh3] (8). In a series of tests, the species 4a鈥?b>h, 5, 6, and 8 were shown to catalyze the hydrogenations of 1-hexene, cyclohexene, and dimethyl itaconate. From the activity of 4a鈥?b>h it is clear that the capability of the carbene鈥揺ther substituents to coordinate to the metal as well as electron-donating substituents on the carbene fragment enhances catalytic activity. Other variations such as in 5, 6, and 8 resulted in terminal-olefin-selective hydrogenation catalysts, although the zwitterionic species 8 showed significantly enhanced activity.