Nitrile N-Selenide (RC⋮NSe) and Isoselenocyanate (RNCSe) Neutrals and Radical Cations by Selenation of Nitriles and Isonitriles: Tandem Mass Spectrometry and ab Initio Studies

Structure, Stability, and Cycloaddition Reactions of Nitrile Selenides

The equilibrium structure, unimolecular reactions, and bimolecular reactions of nitrile selenides (XCNSe, where X = H, F, Cl, Br, CN, CH3) have been investigated using CCSD(T), CCSD(T)//B3LYP, and MR-AQCC//UB3LYP quantum-chemical methods. Nitrile selenides are demonstrated to be stable under isolated conditions at ambient temperature, i.e. in the dilute gas phase or in an inert solid matrix, but unstable in the condensed phase or solutions owing to bimolecular reactions. FCNSe and CH3CNSe cycloaddition with ethynes, ethenes, and nitriles was studied using the MR-AQCC//UB3LYP method. Cycloaddition was predicted to be facile at room temperature with small dipolarophiles.

Gas-phase ion chemistry and organic chemistry-the story of a hybrid six sector mass spectrometer--the "AutoSpec 6F"

The AutoSpec 6F mass spectrometer is a large, floor standing instrument comprising a pair of commercial EBE geometry (AutoSpec) mass spectrometers coupled in series to provide an hybrid EBE-EBE configuration, (E and B being respectively electrostatic and magnetic sectors.) It was designed in close collaboration between Professor R. Flammang and VG Analytical in Manchester, UK. It was equipped with five collision cells and allowed the recording of high energy CID (collision induced dissociation), MIKES (mass analyzed ion kinetic energy spectrometry) and NRMS (neutralization re-ionization mass spectrometry) data as well as consecutive MSn analyses. The field-free regions between sectors allowed the study of unimolecular decomposition products from long-lived metastable ions. The mass spectrometer became even more versatile when an RF-only quadrupole collision cell was installed between the second and the third electric sector. This allowed the study of associative ion/molecule reactions in the low kinetic energy regime. Bimolecular chemical reactions were performed inside the quadrupole cell when a neutral reagent was introduced and the reaction products were analyzed by high energy CID in the downstream sectors. This paper tells the history and summarizes the capabilities of this versatile instrument.

New experiments on HNCSe and HCNSe radical cations

Dissociative ionization of the selenourea Se=C(NH(2))(2) (2) conveniently generates beams of pure isocyanoselenic acid radical cations. The HNCSe(.+) connectivity is established by collisional activation and by associative ion-molecule reactions with dimethyl sulfide or nitric oxide using a large-scale hybrid mass spectrometer.

Mass spectrometric studies of elusive molecules that contain an N(+)-X- bond

This review will be concerned with the gas phase chemistry of 1,2- and 1,3-dipolar systems that contain a carbon-nitrogen bond. Although most of these compounds are stable molecules under normal conditions, certain congeners are reactive species that cannot be prepared using conventional procedures. The isolation and observation of these elusive compounds therefore require appropriate experimental conditions such as those provided by the gas phase of a mass spectrometer. In these experiments, the radical cations, corresponding to the molecule under study, must be prepared via indirect procedures, including dissociative electron ionization, on-line flash-vacuum pyrolysis-mass spectrometry, or ion-molecule reactions. Their characterization is mainly based on collisional activation and ion-molecule reactions. The formation of the corresponding highly reactive neutrals is attempted by neutralization-reionization mass spectrometry. This review presents more than one hundred different molecules together with their methods of preparation and the experiment used to identify them.