Gas‐phase reaction of the aromatic distonic radical cations 4‐Pyr+· and 3‐Pyr+· with amines led to formation of the corresponding amino pyridinium ions 4‐Pyr+NR2 and 3‐Pyr+NR2 through amine addition at the site of the radical, followed by homolytic β‐fragmentation. The reaction efficiencies range from 66‐100% for 4‐Pyr+· and 57‐86% for 3‐Pyr+· , respectively, indicating practically collision‐controlled processes in some cases. Computational studies revealed that the combination of positive charge and spin makes nucleophilic attack by the amine at the site of the radical barrierless and strongly exothermic by about 175 ± 15 kJ mol ‐1 , thereby rendering ‘conventional’ radical pathways through hydrogen abstraction or addition onto π systems less important. Exemplary studies with 4‐Pyr+· showed that this reaction can be reproduced in solution. A similar addition/radical fragmentation sequence occurs also in the gas‐phase reaction of amines with the aliphatic distonic radical cation Oxo+C· , showing that the observed charge‐spin synergism is not limited to aromatic systems.

中文翻译：

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取代性芳基和烷基自由基阳离子与胺的反应：电荷和自旋的作用通过质谱，动力学研究和DFT计算得以揭示

芳族二氢自由基阳离子4-Pyr +·和3-Pyr +·与胺的气相反应通过在自由基的位点加成胺形成相应的氨基吡啶鎓离子4-Pyr + NR2和3-Pyr + NR2 ，然后进行均相β片段化。对于4Pyr +·，反应效率分别为66-100％，对于3Pyr +·，反应效率为57-86％，这表明在某些情况下实际上是碰撞控制的过程。计算研究表明，正电荷和自旋的结合使胺对自由基位点的亲核攻击无障碍且强烈放热约175±15 kJ mol -1，从而通过氢的提取或加成使“常规”的自由基途径发生π系统不太重要。用4-Pyr +·进行的示例性研究表明，该反应可以在溶液中重现。