叔丁基阳离子的从头算/密度泛函理论/广义膺势局域密度近似耦合簇单双激发微扰理论计算研究：实验数据与结构、能量、红外振动频率及13C核磁共振化学位移的比较表明了优选的C(s)构象。

Ab initio/DFT/GIAO-CCSD(T) calculational study of the t-butyl cation: comparison of experimental data with structures, energetics, IR vibrational frequencies, and 13C NMR chemical shifts indicating preferred C(s) conformation.

作者信息

Rasul Golam, Chen Jonathan L, Prakash G K Surya, Olah George A

机构信息

Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, California 90089-1661, USA.

出版信息

J Phys Chem A. 2009 Jun 18;113(24):6795-9. doi: 10.1021/jp903002z.

DOI:10.1021/jp903002z

PMID:19476321

Abstract

The C(s) conformation of the tert-butyl cation 3 was established to be the preferred global energy minimum using a combination of ab initio, DFT, and CCSD(T) methodology with correlation-consistent basis sets. The potential energy surface of methyl rotation involving the C(3v), C(s), and C(3h) forms, however, in accord with previous studies, is quite flat. The computed IR absorptions of 3 indicate that it has the greatest degree of electron donation from C-H bonds into the C(+)-C bonds. The experimental (13)C NMR chemical shifts also agree very well with the experimental data.

摘要

采用从头算、密度泛函理论（DFT）和耦合簇单双激发（CCSD(T)）方法，并结合相关一致基组，确定叔丁基阳离子3的C(s)构象为全局能量最低的首选构象。然而，与先前的研究一致，涉及C(3v)、C(s)和C(3h)形式的甲基旋转势能面相当平坦。计算得到的3的红外吸收表明，它具有从C-H键到C(+)-C键的最大程度的电子给予。实验测得的(13)C NMR化学位移也与实验数据非常吻合。