Proton Transfer Processes in 2-Butenenitrile Dimer Cation Studied by Mass-Selective Infrared Spectroscopy

Abstract

2-Butenenitrile (2-Bu) is a recently discovered crucial interstellar molecule. Herein, an abnormal NH band was observed in the infrared spectrum of the 2-Bu dimer cation, suggestive of a proton transfer reaction within the cluster. Through a comprehensive theoretical analysis of the IR spectrum of (2-Bu) 2 + , we discovered not only the formation of a new C−N bond through the attachment of one 2-Bu to another but also the occurrence of a proton transfer reaction in the cluster. This proton was identified as originating from the methyl group of the attaching 2-Bu in the cluster based on the analysis of IR spectra of (2-Bu) + and [2-Buacrylonitrile (AN)] + . Furthermore, the detailed reaction process of this ion−molecule reaction is examined with theoretical calculation. This finding contributes significantly to our deeper understanding of ion− molecule reactions in the gas phase and the formation of nitrogencontaining prebiotic molecules in the interstellar medium.