同分异构效应的14N核四极共振研究

为探究同分异构现象对含氮化合物的¹⁴N核四极共振（NQR）特征的影响，基于核四极共振基本原理和杂化轨道价键理论，以烟酸和异烟酸这两种互为同分异构体的羧基吡啶为研究对象，从共振频谱、特征参数和杂化效应3个方面，对分子结构异同所导致的¹⁴N NQR特征异同进行了研究。通过试验结果的对比分析，发现分子结构的异同使¹⁴N NQR特征呈现许多异同，具体表现为：就共振频谱而言，相似性主要体现于频谱形状，而差异性则主要体现于低频频谱的共振频率；就特征参数而言，相似性主要体现于四极耦合常数，而差异性则主要体现于不对称参数；就杂化效应而言，相似性主要体现于杂化形式，而差异性则主要体现于轨道占据。

14 N NQR Study of Isomeric Effect

In order to explore the isomeric effect on 14 N nuclear quadrupole resonance (NQR) characteristics of nitrogenous compounds ,the nicotinic and isonicotinic acids , serving as mutual isomers that both belong to carboxyl pyridines , were taken as research objects based on the NQR fundamental principles and hybrid orbital valence bond theories .In this paper ,the similarities and differences of 14 N NQR characteristics due to those of molecular structures were investigated from resonance spectra ,charac‐teristic parameters and hybrid effects .According to the comparative analysis about the experimental results ,it can be found that there are plenty of similarities and differences in 14 N NQR characteristics owing to the molecular isomerism .Or rather ,in terms of resonance spectra ,the similarities are reflected in spectral shape with differences in res‐onance point of the spectra for low frequencies .As far as characteristic parameters ,the similarities are embodied in quadrupole coupling constant with differences in asymmetry parameter .With regard to hybrid effects ,the similarities are concretized in hybrid form with differences in orbital occupation .