Second‐order polarization propagator approximation (SOPPA) and density functional theory (DFT) B3LYP computations revealed the presence of giant 3JHCCH couplings, up to more than 60 Hz, in conjugated quinonoid systems, very far above the typical limit of ~15 Hz. Strong hyperconjugative interactions of the C–H σ orbitals with the quinonoid 8‐e− π system, which allows effective propagation of the spin polarization, seem to be responsible for those extraordinarily large couplings. Computation on several model systems showed the additive nature of the contributions from the available coupling paths to the total coupling.

中文翻译：

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3 J HCCH 耦合可以有多大？醌型系统中巨型邻位耦合的预测

二阶极化传播器近似 (SOPPA) 和密度泛函理论 (DFT) B3LYP 计算揭示了在共轭醌系统中存在高达 60 Hz 以上的巨大 3JHCCH 耦合，远高于典型的 ~15 Hz 极限。C-H σ 轨道与醌型 8-e-π 系统的强超共轭相互作用，允许自旋极化的有效传播，似乎是造成这些异常大耦合的原因。对几个模型系统的计算显示了可用耦合路径对总耦合的贡献的可加性。