Ab initio calculations of the NMR spectra of [1.1.1]propellane and bicyclo[1.1.1]pentane
Ab initio calculations of the NMR spectra of [1.1.1]propellane and bicyclo[1.1.1]pentane
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DOI：
10.1039/b100441g
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发表时间：
2001
影响因子：
3.3
通讯作者：
M. Pecul;H. Dodziuk;M. Jaszuński;O. Lukin;J. Leszczynski
中科院分区：
文献类型：
--
作者：
M. Pecul;H. Dodziuk;M. Jaszuński;O. Lukin;J. Leszczynski
计算得到了[1.1.1]螺桨烷和双环[1.1.1]戊烷的所有NMR屏蔽常数和自旋-自旋耦合常数的新的高水平从头算值，并与已有的理论结果和实验数据进行了比较.电子相关效应被考虑在内，并适用于NMR研究的大基组。屏蔽常数的结果主要取决于基组，而自旋-自旋耦合常数，特别是碳-碳耦合，是非常敏感的电子相关效应。除了[1.1.1]螺桨烷中的桥头-桥头碳耦合常数外，计算的NMR参数与已知的实验值吻合得很好。我们对这个常数的最佳估计不同于[1.1.1]螺桨烷的实验值，并讨论了这种差异的可能解释。
New high-level ab initio values of all the NMR shielding and spin–spin coupling constants in [1.1.1]propellane and bicyclo[1.1.1]pentane are obtained and compared with previous theoretical results and available experimental data. Electron correlation effects are taken into account and large basis sets suitable for NMR studies are applied. The results for the shielding constants depend primarily on the basis set, while the spin–spin coupling constants, in particular for the carbon–carbon coupling, are very sensitive to electron correlation effects. The computed NMR parameters agree well with the known experimental values, with the exception of the bridgehead–bridgehead carbon coupling constant in [1.1.1]propellane. Our best estimates of this constant differ from the experimental value for a substituted [1.1.1]propellane, and possible explanations of this discrepancy are discussed.