Sensing the ortho Positions in C6Cl6 and C6H4Cl2 from Cl2− Formation upon Molecular Reduction

• Published in: Molecules (Basel, Switzerland) Switzerland), 2022-07, Vol.27 (15), p.4820
• Main Authors: Kumar, Sarvesh, Romero, José, Probst, Michael, Maihom, Thana, García, Gustavo, Limão-Vieira, Paulo
• Format: Article
• Language: English
• Subjects: Aromatic compounds; By products; charge transfer; Chlorine; collision induced dissociation; Dichlorobenzene; Electron transfer; Energy; Energy dissipation; geometric effect; Hexachlorobenzene; Investigations; Mass spectrometry; Mass spectroscopy; Metabolism; Polyatomic molecules; Potassium
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules27154820

The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl2−. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl2− formation can only occur in 1,2-C6H4Cl2, where the two closest C–Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C–Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation.