McCann D M, Stephens P J, Cheeseman J R
Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0482, USA.
J Org Chem. 2004 Dec 10;69(25):8709-17. doi: 10.1021/jo048571n.
The recently developed Gauge-Invariant (Including) Atomic Orbital (GIAO) based Time-Dependent Density Functional Theory (TDDFT) methodology for the calculation of transparent spectral region optical rotations of chiral molecules provides a new approach to the determination of absolute configurations. Here, we discuss the application of the TDDFT/GIAO methodology to chiral alkanes. We report B3LYP/aug-cc-pVDZ calculations of the specific rotations of the 22 chiral alkanes, 2-23, of well-established Absolute Configuration. The average absolute deviation of calculated and experimental alpha values for molecules 2-22 is 24.8. In two of the molecules 2-23, trans-pinane, 10, and endo-isocamphane, 13, the sign of alpha is incorrectly predicted. Our results demonstrate that absolute configurations of alkanes can be reliably assigned by using B3LYP/aug-cc-pVDZ TDDFT/GIAO calculations if, but only if, alpha is significantly greater than 25. In the case of (-)-anti-trans-anti-trans-anti-trans-perhydrotriphenylene, 1, alpha is -93 and TDDFT/GIAO calculations reliably lead to the absolute configuration R(-).
最近开发的基于规范不变（包括）原子轨道（GIAO）的含时密度泛函理论（TDDFT）方法，用于计算手性分子在透明光谱区域的旋光性，为确定绝对构型提供了一种新方法。在此，我们讨论TDDFT/GIAO方法在手性烷烃中的应用。我们报告了对22种手性烷烃（2 - 23）的比旋光度进行的B3LYP/aug - cc - pVDZ计算，这些烷烃具有已确定的绝对构型。对于分子2 - 22，计算值与实验α值的平均绝对偏差为24.8。在2 - 23中的两个分子，即反式蒎烷（10）和内型异莰烷（13）中，α的符号被错误预测。我们的结果表明，只有当α显著大于25时，使用B3LYP/aug - cc - pVDZ TDDFT/GIAO计算才能可靠地确定烷烃的绝对构型。对于（-）-反式-反式-反式-反式-全氢三亚苯（1），α为 - 93，TDDFT/GIAO计算可靠地得出绝对构型为R（-）。
