• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Computational Replication of the Primary Isotope Dependence of Secondary Kinetic Isotope Effects in Solution Hydride-Transfer Reactions: Supporting the Isotopically Different Tunneling Ready State Conformations
【24h】

Computational Replication of the Primary Isotope Dependence of Secondary Kinetic Isotope Effects in Solution Hydride-Transfer Reactions: Supporting the Isotopically Different Tunneling Ready State Conformations

机译：溶液氢化物转移反应中次级动力学同位素效应的主要同位素依赖性的计算复制：支持同位素不同的隧穿就绪态构象

获取原文
获取原文并翻译 | 示例
       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We recently reported a study of the steric effect on the 1 isotope dependence of 2 degrees KIEs for several hydride-transfer reactions in solution (J Am. Chem. Soc. 2015, 137, 6653). The unusual 2 KIEs decrease as the 1 isotope changes from H to D, and more in the sterically hindered systems. These were explained in terms of a more crowded tunneling ready state (TRS) conformation in D-tunneling, which has a shorter donor acceptor distance (DAD) than in H-tunneling. To examine the isotopic DAD difference explanation, in this paper, following an activated motion assisted H-tunneling model that requires a shorter DAD in a heavier isotope transfer process, we computed the 2 KIEs at various H/D positions at different DADs (2.9 angstrom to 3.5 angstrom) for the hydride-transfer reactions from 2-propanol to the xanthylium and thioxanthylium ions (Xn and TXn(+)) and their 9 -phenyl substituted derivatives (Ph(T)Xn+). The calculated 2 KIEs match the experiments and the calculated DAD effect on the 2 KIEs fits the observed 1 isotope effect on the 2 KIEs. These support the motion-assisted H-tunneling model and the isotopically different TRS conformations. Furthermore, it was found that the TRS of the sterically hindered Ph(T)Xn(+) system does not possess a longer DAD than that of the (T)Xn(+) system. This predicts a no larger 1 KIE in the former system than in the latter. The observed 1 KIE order is, however, contrary to the prediction. This implicates the stronger DAD-compression vibrations coupled to the bulky Ph(T)Xn(+) reaction coordinate.
机译：我们最近报道了溶液中几种氢化物转移反应对2度KIE的1同位素依赖性的空间效应的研究（J Am。Chem。Soc。2015，137，6653）。当1个同位素从H变为D时，不寻常的2个KIE减少，而在位阻系统中，更多。这些解释是根据D隧道中更拥挤的隧道就绪状态（TRS）构象来解释的，它比H隧道中的施主受体距离（DAD）短。为了检查同位素DAD差异的解释，在本文中，在一个激活的运动辅助H隧道模型中，在较重的同位素转移过程中需要一个较短的DAD，我们计算了在不同D / D（2.9埃）上各个H / D位置的2个KIE氢转移到2-丙醇到xanthylium和thioxanthylium离子（Xn和TXn（+））及其9-苯基取代的衍生物（Ph（T）Xn +）的氢化物转移反应中。计算出的2个KIE与实验相符，计算出的2种KIE的DAD效应与2种KIE的观测到的1种同位素效应相吻合。这些支持运动辅助H隧道模型和同位素不同的TRS构象。此外，发现位阻Ph（T）Xn（+）系统的TRS不具有比（T）Xn（+）系统更长的DAD。这预示前者系统中的1 KIE不会比后者更大。但是，观察到的1 KIE阶与预测相反。这意味着与庞大的Ph（T）Xn（+）反应坐标耦合的DAD压缩振动更强。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号