Ion Cyclotron Resonance Investigations of Negative Ion-Molecule Reactions

chapter I Ion cyclotron resonance techniques are employed in the examination of the gas phase reactions of PF3 and OPF3 with anionic bases, including NH2-, OH-, CH3 CH2O-, HNO-, HS-, SF6-, and SF5-. Evidence is presented which suggests that all reactions proceed by initial attack at phosphorous, with products resulting from decomposition of chemically activated intermediates. The energetics of intermediates inferred in these processes are related to the Lewis acidities of OPF3 and PF3. With fluoride ion as a reference base, OPF3 is found to be more acidic than PF3 , with D(OPF3-F-) = 58.9 ± 0.4 kcal/mole and D(PF3-F-) = 50 ± 5 kcal/mol. Chapter II Ion cyclotron resonance techniques are employed to determine the gas phase Bronsted and Lewis acidities as well as the Bronsted basicity of l-methyl-1, 4 dihydroborabenzene, CH3BC5H6. The ring proton is found to be highly acidic with PA(CH3BC5H5) = 337 ± 3 kcal/mol. This acidity results from the formation of 6π electron aromatic anion CH3BC5H5-, which is isoelectronic with toluene. Both the Lewis acidity and proton basicity of the parent molecule suggest that there is little interaction between the diene π system and the electron deficient boron. This is further confirmed by the similarity of both negative and positive ion chemistry of the borabenzene to that of aliphatic boranes. Chapter III Ion cyclotron resonance techniques are employed in the investigation of positive and negative ion formation and ion molecule reactions in sulfuryl halides SO2XY(X, Y = Cl, F). Positive ion reactivity is discussed in terms of the relative Cl and F bond strengths in these species and possible structures of ionic intermediates and products. Electron attachment processes generate halide ion donors such as F2-, Cl2-, SO2F- and SO2 Cl- from sulfuryl halides. Negative ion reactivity is dominated by halide transfer reactions. Halide transfer reactions in mixtures with H CN and HCl are examined in an attempt to quantify D(SO2-F-) and D(SO2-C-).