title: Interpretation of alkyl diselenide and selenosulfenate mass spectra.
abstract: The mass spectral fragmentation of aliphatic diselenides and selenosulfenates is analyzed to gain a better understanding of the behavior of these species. The main fragmentation pathways of these species include the fragmentation along the Se?C bond, fragmentation along the Se?Se or Se?S bonds and intra-molecular rearrangements. In general, negative ionization favors the fragmentation along the Se?Se or Se?S bonds while positive ionization leads to stable molecular ions. Density functional theory calculations of bond dissociation energies and molecular orbital analysis was undertaken to explain the observed trends in molecular fragmentation. Besides the analysis of molecular fragmentation, a phenomenon of molecular association in negative electron impact and positive chemical ionization conditions was observed and investigated using a high resolution time-of-flight mass spectrometer. Molecular association that occurs during the ionization of species includes the formation of symmetrical diselenides from asymmetrical selenosulfenates and formation of alkylseleno adducts from the corresponding diselenides. For species which is hard to resolve by mass analysis, such as isobars of CHSe, CH(2)Se, and CH(3)Se, the isotope pattern superimposition procedure was applied to define the overlapping clusters.
authors.affiliation: Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, USA.
authors.forename: Juris
authors.initials: J
authors.lastname: Meija
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Beck
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Caruso
mesh_terms: D007477:Ions / Q000737:chemistry; D018036:Selenium Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D007477:Ions; D018036:Selenium Compounds