Palladium(II) Containing 纬-Keggin Silicodecatungstate That Efficiently Catalyzes Hydration of Nitriles
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- 作者：Tomohisa Hirano ; Kazuhiro Uehara ; Keigo Kamata ; Noritaka Mizuno
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：April 11, 2012
- 年：2012
- 卷：134
- 期：14
- 页码：6425-6433
- 全文大小：451K
- 年卷期：v.134,no.14(April 11, 2012)
- ISSN：1520-5126
文摘
A mixture of Pd(OAc)2 and TBA4[纬-SiW10O34(H2O)2] (TBA-SiW10, TBA = [(n-C4H9)4N]+) showed high catalytic activities for hydration of various kinds of structurally diverse nitriles including aromatic, aliphatic, heteroaromatic, and double bond-containing ones. For hydration of 3-cyanopyridine, the turnover frequency was 860 h鈥?, and the turnover number reached up to 670. A dipalladium-substituted 纬-Keggin silicodecatungstate, [纬-H2SiW10O36Pd2(OAc)2]4鈥?/sup> (I), was successfully synthesized by the reaction of [纬-SiW10O34(H2O)2]4鈥?/sup> with Pd(OAc)2 in a mixed solvent of acetone and water. The crystal structure of I was a monomeric, dipalladium-substituted, 纬-Keggin silicodecatungstate with bidentate acetate ligands. Compound I showed similar activities and selectivities to those of a simple mixture of Pd(OAc)2 and TBA-SiW10. The kinetic, mechanistic, and density functional theory calculation studies show that the dipalladium site plays an important role in the present hydration, and the nucleophilic attack of a hydroxide or water to the nitrile carbon atom is included in the rate-determining step.