Martin N H, Brown J D, Nance K H, Schaefer H F, Schleyer P R, Wang Z X, Woodcock H L
Department of Chemistry, University of North Carolina at Wilmington, Wilmington, NC 28403-5932, USA.
Org Lett. 2001 Nov 29;3(24):3823-6. doi: 10.1021/ol016500u.
GIAO-HF and IGLO-DFT computations of isotropic magnetic shieldings were used to map the NMR shielding environments of small molecules exemplifying selected organic functional groups. Two different probes were employed: a methane molecule and NICS (nucleus-independent chemical shifts) based on computed absolute isotropic shieldings. The reason for the different results obtained using these two probes is perturbation of the wave function by the proximity of methane to the pi bond, as analyzed by the localized orbital contributions to the shieldings. [structure: see text]
使用GIAO-HF和IGLO-DFT对各向同性磁屏蔽进行计算，以绘制小分子的核磁共振屏蔽环境图，这些小分子代表了选定的有机官能团。采用了两种不同的探针：甲烷分子和基于计算得到的绝对各向同性屏蔽的NICS（核独立化学位移）。使用这两种探针得到不同结果的原因是，如通过屏蔽的定域轨道贡献所分析的，甲烷靠近π键会对波函数产生微扰。[结构：见正文]
