Department de Química Física I Inorgànica, Universitat Rovira I Virigli, Tarragona, Spain.
ChemSusChem. 2009;2(8):769-79. doi: 10.1002/cssc.200900079.
Metallic Ru, Rh, and Ir nanoparticles were prepared by the decomposition of organometallic precursors under H(2) pressure in the presence of 1,3-diphosphite ligands, derived from carbohydrates, as stabilizing agents. Structural modifications to the diphosphite backbone were found to influence the nanoparticles' size, dispersion, and catalytic activity. In the hydrogenation of o- and m-methylanisole, the Rh nanoparticles showed higher catalytic activity than the corresponding Ru nanoparticles. The Ir nanoparticles presented the lowest catalytic activity of the series. In all cases, the hydrogenation of o-methylanisole gave total selectivity for the cis-product, however, the ee of the product was always less than 6 %. A maximum of 81 % cis-selectivity was obtained for the hydrogenation of m-methylanisole, however, no asymmetric induction was observed. These results show that the catalytic activity is affected by a combination of influences from the substrate, the diphosphite ligands, and the metallic nanoparticles.
采用碳水化合物衍生的 1,3-双膦配体作为稳定剂，在氢气压力下通过有机金属前体的分解制备了金属 Ru、Rh 和 Ir 纳米粒子。发现双膦配体骨架的结构修饰会影响纳米粒子的尺寸、分散性和催化活性。在邻位和间位甲基苯甲醚的加氢反应中，Rh 纳米粒子表现出比相应的 Ru 纳米粒子更高的催化活性。Ir 纳米粒子在该系列中表现出最低的催化活性。在所有情况下，邻位甲基苯甲醚的加氢反应均得到顺式产物的完全选择性，但产物的 ee 值始终小于 6%。间位甲基苯甲醚加氢反应的最高顺式选择性达到 81%，但没有观察到不对称诱导。这些结果表明，催化活性受到底物、双膦配体和金属纳米粒子的综合影响。
