title: What ion is generated when ionizing acetonitrile?
abstract: It has long been assumed that ionizing neutral acetonitrile produces ions with the same atomic connectivity, CH(3)CN(+*). Recent calculations on the C(2)H(3)N(+*) potential energy surface have suggested that it may be difficult to generate pure CH(3)CN(+*) when ionizing acetonitrile. We have probed the interconversion of CH(3)CN(+*) and its lower energy isomer CH(2)CNH(+*) by calculation, collision-induced dissociation mass spectrometry and ion-molecule reaction. The latter ion, ionized ketenimine, is co-generated upon electron or chemical ionization of neutral acetonitrile in the ion source of a mass spectrometer. An estimate of the ratio of the two isomers can be obtained from their respective ion-molecule reactions with CO(2) or COS. CH(3)CN(+*) reacts by proton-transfer with CO(2) and charge transfer with COS, whereas CH(2)CNH(+*) is unreactive.
authors.forename: Giulia
authors.initials: G
authors.lastname: de Petris
authors.forename: Simonetta
authors.initials: S
authors.lastname: Fornarini
authors.forename: Maria Elisa
authors.initials: ME
authors.lastname: Crestoni
authors.forename: Anna
authors.initials: A
authors.lastname: Troiani
authors.forename: Paul M
authors.initials: PM
authors.lastname: Mayer
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D004583:Electrons; D007477:Ions; D007700:Kinetics; D013058:Mass Spectrometry; D013057:Spectrum Analysis
chemical_list: D000097:Acetonitriles; D007477:Ions; C032159:acetonitrile