The understanding of selectivity in reactions exhibiting nonstatistical dynamics is impeded by the limitations of trajectory studies with regard to nuclear quantum effects, especially tunneling. We described here the use of ring-polymer molecular dynamics (RPMD) to account for an unusual regiochemical isotope effect on the regioselectivity of hydroborations of alkenes with BH₃/BD₃. RPMD is able to account for the experimental observation, while statistical approaches and classical trajectories fail. The combination of experiment and RPMD trajectories suggests that tunneling in the initial collision of reactants is the major source of the nonstatistical selectivity.

中文翻译：

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核量子对硼氢化选择性性质的影响：第一次碰撞隧穿的实验效应


由于轨迹研究在核量子效应（尤其是隧穿效应）方面的局限性，阻碍了对表现出非统计动力学的反应中选择性的理解。我们在这里描述了使用环聚合物分子动力学 （RPMD） 来解释对 BH₃/BD₃ 的烯烃硼氢化物的区域选择性的不寻常区域化学同位素效应。RPMD 能够解释实验观察，而统计方法和经典轨迹则失败了。实验和 RPMD 轨迹的结合表明，反应物初始碰撞中的隧穿是非统计选择性的主要来源。