Molecular Charge-Transfer Cross Sections and Their Correlation with Reactant Ion Structures

Charge-transfer cross sections have been obtained by using time-of-flight techniques, and results correlated with reaction energetics and theoretical structures computed by self-consistent field-molecular orbital methods. Ion recombination energies, structures, heats of formation, reaction energy defects, and 3.0-keV charge-transfer cross sections are presented for reactions of molecular and fragment ions produced by electron bombardment ionization of CH30CH, and CH$l molecules. Relationships between experimental cross sections and reaction energetics involving different ion structures are discussed.

A Semiempirical Transition State Structure for the First Step in the Alkaline Hydrolysis of Cocaine. Comparison between the Transition State Structure, the Phosphonate Monoester Transition State Analog, and a Newly Designed Thiophosphonate Transition State Analog

Semiempirical molecular orbital calculations have been performed for the first step in the alkaline hydrolysis of the neutral benzoylester of cocaine. Successes, failures, and limitations of these calculations are reviewed. A PM3 calculated transition state structure is compared with the PM3 calculated structure for the hapten used to induce catalytic antibodies for the hydrolysis of cocaine. Implications of these calculations for the computer–aided design of transition state analogs for the induction of catalytic antibodies are discussed.

AM1 and PM3 Calculations of the Potential Energy Surfaces for CH2OH Reactions with NO and NO2

The AM1 and PM3 molecular orbital methods have been utilized to investigate the reactions of CH20H with NO and NO2 PM3 and AM1 calculated heats of formation differ from experimental values by 8.6 and 18.8 kcal mol-', respectively. The dominant reaction of CH20H with NO is predicted to produce the adduct HOCH2N0, supporting the hypothesis of Pagsberg, Munk, Anastasi, and Simpson. Calculated activation energies for the NO2 system predict the formation of the adducts HOCH2N02 and HOCH20N0. In addition, the PM3 calculations predict that the abstraction reaction producing CH20 and HN02 is more likely than one producing CH20 and HONO from reactions of CH20H with NO2.

Sensitivity of charge transfer reactions to hydrocarbon ion structures

Charge transfer reactivities of hydrocarbon ions have been measured with time-of-flight techniques, and results correlated with theoretical structures computed by self-consistent field molecular orbital methods. Recombination energies, ion structures, heats of formation, reaction energetics and relative charge transfer cross-sections are presented for molecular and fragment ions produced by electron bombardment ionization of CH4, C2H4, C2H6, C3H8 and C4H10 molecules. Even-electron bridged cations have low ion recombination energies and relatively low charge transfer cross-sections as compared with odd-electron hydrocarbon cations.

Doubly-charged gas phase cations

Unique features of doubly-charged stable organic ions are examined and the results correlated with experimental observations. Self-consistent field molecular orbital methods are used to compute structures and stabilities of CnH 2 2+ (n=2–9) ions which are prominent in electron impact ionization of hydrocarbon molecules. A simple curve crossing model is employed to rationalize charge transfer reactions of these ions.