Selvaraj Muthuamirthambal, Subramani Arun, Ramanathan Karthick, Richter Robert, Pal Nitish, Bolognesi Paola, Avaldi Lorenzo, Kadhane Umesh R
Indian Institute of Space Science and Technology, Trivandrum, Kerala, India.
Elettra-Sincrotrone Trieste, Italy.
Phys Chem Chem Phys. 2024 Jun 12;26(23):16540-16549. doi: 10.1039/d3cp05882d.
The goals of this work are to attempt to decipher if an aniline dication can isomerize to a picoline dication in a given astrochemical environment and if the dissociation of such dications could be a source of kinetically hot fragment ions, some of which could be of significance in the interstellar medium. Toward this purpose, the VUV-induced dication dissociation was investigated experimentally using ion-ion coincidence and computationally by optimizing various pathways. Contrary to previous reports, we show here that the dication of aniline is structurally too weak to retain its ring structure while following the dissociation pathways. A fragile open ring structure could lead to all the experimentally observed pathways of noticeable intensity. The significance of this, especially in terms of molecular dynamics, can be assessed by the fact that all the transformations were facilitated by specific hydrogen migration. A clear selectivity is seen where the dication of aniline was found to prefer a rearrangement of hydrogen within the ring rather than transferring from nitrogen to the ring, which is conventionally expected and has to do with the charge state and charge localization.
这项工作的目标是试图弄清楚在给定的天体化学环境中，苯胺二价阳离子是否会异构化为甲基吡啶二价阳离子，以及这种二价阳离子的解离是否可能是动力学热碎片离子的一个来源，其中一些离子可能在星际介质中具有重要意义。为此，利用离子 - 离子符合技术对真空紫外诱导的二价阳离子解离进行了实验研究，并通过优化各种途径进行了计算研究。与之前的报道相反，我们在此表明，苯胺二价阳离子的结构过于脆弱，以至于在遵循解离途径时无法保持其环状结构。一种脆弱的开环结构可能导致所有实验观察到的具有显著强度的途径。这一点的重要性，尤其是在分子动力学方面，可以通过所有转化都由特定的氢迁移促进这一事实来评估。可以看到一种明显的选择性，即发现苯胺二价阳离子更喜欢环内氢的重排，而不是从氮转移到环上，这是传统上预期的，并且与电荷状态和电荷局域化有关。
