Vacuum Ultraviolet Photoionization Induced Proton Migration and Formation of a New C-N Bond in Pyridine Clusters Revealed by Infrared Spectroscopy and Mass Spectrometry

Jun Ying Feng, Yuan Pern Lee, Henryk Arnold Witek, Takayuki Ebata

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The structures and reactions of pyridine (Pyd) cluster cations in a supersonic molecular beam generated upon photoionization at 9.2-9.4 eV were investigated by infrared (IR) action spectroscopy. The mass spectrum showed prominent peaks of (Pyd)m+ and H+(Pyd)m, m = 1-5. In the pyridine/pyridine-d5 mixture, the mass pattern indicated that H+ and D+ migrated during the formation and dissociation of the cluster cations. The IR photodissociation spectra of both (Pyd)2+ and H+(Pyd)2 revealed a N-H stretching band near 3400 cm-1, indicating that their structures are 1-(2-pyridyl)pyridin-1-ium and pyridinium-pyridine, respectively. Observation of the former product implies that the reaction proceeds via an α-distonic cation intermediate, while the latter product is formed via proton migration. The IR spectra of (Pyd)m+ and H+(Pyd)m, m ≥ 3, suggested that these clusters consist of a covalently bound (Pyd)2+ or H+(Pyd)2 core, respectively, with additional pyridines attached to them via hydrogen bonds and/or weak dispersive interactions.

Original languageEnglish
Pages (from-to)4936-4943
Number of pages8
JournalThe journal of physical chemistry letters
Volume12
Issue number20
DOIs
StatePublished - 27 May 2021

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