Hyperconjugative Nature of the Cis Effect in N2F2: Computational Chemistry Teaching Case
WANG Jin-Zhao1, LIU Peng2, YANG Yi-Ying1, ZHU Rong-Xiu1, MA Yu-Chen1, ZHANG Dong-Ju1**
1. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China; 2. School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China
Abstract The exploration of structure-property relationships occupies a central role in undergraduate chemistry education,and the evaluation of the relative stability of molecular isomers is a typical example of this concept.Difluorodiazene(N2F2) exists in both cis and trans forms,however,unlike typical cis-trans systems(such as diazene,N2H2),it exhibits an anomalous behavior in which the cis isomer is more stable than the trans isomer,a phenomenon known as the cis effect.In this work,N2F2 is used as a teaching case to illustrate how computational chemistry can be employed to probe molecular stability.Through quantum chemical calculations,we examine the contribution of hyperconjugation to the stability difference between the cis and trans isomers,and reveal the electronic structural origin of this anomaly.This case study is intended to guide students beyond empirical reasoning,deepen their understanding of structure-property relationships,and provide a reference for implementing inquiry-based teaching in foundational chemistry courses.
WANG Jin-Zhao, LIU Peng, YANG Yi-Ying, ZHU Rong-Xiu, MA Yu-Chen, ZHANG Dong-Ju. Hyperconjugative Nature of the Cis Effect in N2F2: Computational Chemistry Teaching Case[J]. Chinese Journal of Chemical Education, 2026, 47(10): 85-91.
