Department of Chemistry, Faculty of Science and Center of Nanotechnology, Kasetsart University Research and Development Institute, Kasetsart University, Bangkok, Thailand.
J Phys Chem A. 2011 Nov 17;115(45):12486-92. doi: 10.1021/jp205985v. Epub 2011 Sep 26.
Carbonyl-ene reactions, which involve C-C bond formation, are essential in many chemical syntheses. The formaldehyde-propene reaction catalyzed by several of the group 11 metal cations, Cu(+), Ag(+), and Au(+) exchanged on the faujasite zeolite (metal-FAU) has been investigated by density functional theory at the M06-L/6-31G(d,p) level. The Au-FAU exhibits a higher activity than the others due to the high charge transfer between the Au and the reactant molecules, even though it is located at a negatively charged site of the zeolite. This site enables it to compensate for the charge of the Au(+) ion. The NBO analysis reveals that the 6s orbital of the Au atom plays an important role, inducing a charge on the probe molecules. Moreover, the effect of the zeolite framework makes the Au-FAU more active than the others by stabilizing the high charge induced transition structure. The activation energy of the reaction catalyzed by Au-FAU is 13.0 kcal/mol whereas that of Cu and Ag-FAU is found to be around 17 kcal/mol. The product desorption needs to be improved for Au-FAU; however, we suggest that catalysts with high charge transfer might provide a promising activity.
羰基-ene 反应涉及 C-C 键的形成，在许多化学合成中至关重要。通过密度泛函理论在 M06-L/6-31G(d,p)水平上研究了几种 Group 11 金属阳离子（Cu(+)、Ag(+)和 Au(+)）交换的丝光沸石（金属-FAU）催化的甲醛-丙烯反应。由于 Au 与反应物分子之间的高电荷转移，Au-FAU 比其他的具有更高的活性，尽管它位于沸石的带负电荷的位置上。该位置使其能够补偿 Au(+)离子的电荷。NBO 分析表明，Au 原子的 6s 轨道起着重要作用，诱导探针分子带电。此外，沸石骨架的作用通过稳定高电荷诱导的过渡结构使 Au-FAU 比其他的更具活性。Au-FAU 催化反应的活化能为 13.0 kcal/mol，而 Cu 和 Ag-FAU 的活化能约为 17 kcal/mol。需要改进 Au-FAU 的产物解吸；然而，我们建议具有高电荷转移的催化剂可能提供有前途的活性。
