Ion Cyclotron Resonance Investigations of Negative Ion-Molecule Reactions

Citation

Sullivan, Sally Anne (1978) Ion Cyclotron Resonance Investigations of Negative Ion-Molecule Reactions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/mk9r-2065. https://resolver.caltech.edu/CaltechTHESIS:08012025-171813911

Abstract

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^-).

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