The isomerizations of 3-aza-3-ium-dihydrobenzvalene, 3,4-diaza-3-ium-dihydrobenzvalene, and 3,4-diaza-diium-dihydrobenzvalene to their respective cyclic-diene products were studied using electronic structure methods with a multiconfigurational wave function and several single reference methods. Transition states for both the allowed (conrotatory) and forbidden (disrotatory) pathways were located. The conrotatory pathways of each structure all proceed through a cyclic intermediate with a trans double bond in the ring: this trans double bond destroys the aromatic stabilization of the π electrons due to poor orbital overlap between the cis and trans π bonds. The 3,4-diaza-3-ium-dihydrobenzvalene structure has C₁ symmetry, and there are four separate allowed and forbidden pathways for this structure. The 3-aza-3-ium-dihydrobenzvalene structure is C_s symmetric, and there are two separate allowed and forbidden pathways for this structure. For 3,4-diaza-3,4-diium-dihydrobenzvalene, there was a single allowed and single forbidden pathway due to the C_2v symmetry. The separation of the barrier heights for all three molecules was studied, and we found the difference in activation barriers for the lowest allowed and lowest forbidden pathways in 3,4-diaza-3-ium-dihydrobenzvalene, 3-aza-3-ium-dihydrobenzvalene, and 3,4-diaza-diium-dihydrobenzvalene to be 9.1, 7.4, and 3.7 kcal/mol, respectively. The allowed and forbidden barriers of 3,4-diaza-diium-dihydrobenzvalene were separated by 3.7 kcal/mol, which is considerably less than the 12–15 kcal/mol expected based on the orbital symmetry rules. The addition of the secondary ammonium group tends to shift the conrotatory and disrotatory barriers up in energy (∼12–14 kcal/mol (conrotatory) and 5–10 kcal/mol (disrotatory) per secondary NH₂ group) relative to the barriers of dihydrobenzvalene, but there is negligible effect on E,Z to Z,Z isomerization barriers, which remain in the expected range of greater than 4 kcal/mol.

中文翻译：

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3-Aza-3-ium-dihydrobenzvalene，3,4-Diaza-3-ium-dihydrobenzvalene和3,4-Diaza-二氢二氢苯并戊烯

使用电子结构方法研究了3-氮杂3-氮-二氢苯并戊烯，3,4-二氮杂3-二氢苯并戊烯和3,4-二氮杂-二氢二苯并戊烯异构化成各自的环状二烯产物。多配置波动函数和几种单一参考方法。确定了允许（旋转）和禁止（旋转）路径的过渡状态。每个结构的旋转路径都通过在环中具有反式双键的环状中间体进行：该反式双键由于顺式和反式π键之间较弱的轨道重叠而破坏了π电子的芳族稳定性。3,4-二氮杂-3-ium-二氢苯并戊烯结构的碳原子数为₁对称性，并且此结构有四个单独的允许和禁止途径。3-氮杂-3-鎓-二氢苯并戊烯结构是C _s对称的，并且该结构有两个独立的允许和禁止途径。对于3,4-diaza-3,4-diium-dihydro-benzvalene，由于C _{2 v}，存在单个允许和单个禁止的途径对称。研究了所有三种分子的势垒高度的分离，我们发现了3,4-二氮杂-3-ium-二氢苯并戊烯，3-氮杂-3-ium-二氢苯并戊烯和3,4-二氮杂-二氮杂-二氢苯并戊烯分别为9.1、7.4和3.7 kcal / mol。3,4-二氮杂-二氮杂-二氢苯并戊烯的允许和禁止壁垒之间的间距为3.7 kcal / mol，这大大小于根据轨道对称性规则预期的12-15 kcal / mol。仲铵基团的添加倾向于使旋转和旋转障碍的能量向上移动（每个NH ₂约为12-14 kcal / mol（旋转）和5-10 kcal / mol（旋转））。相对于二氢苯并戊烯的阻挡层，但是对E，Z至Z，Z异构化阻挡层的影响可忽略不计，其保持在大于4kcal / mol的预期范围内。