Microscopic Mechanisms And Kinetic Studies On The Reactions Of Two Categories Anion With Small Neutral Molecules In Gas Phase

Gas-phase anion-molecule reaction plays an important role in discovering thereaction mechanisms of the new synthetic and measuring some importantthermochemical values because they are in general more rapidly, intense and selectivethan their solution analogues. Thus, it favored by many chemical researchers. Thispaper studies the reactions about CH3OCl with Cl-and the N2O with butadiene thatboth reactions are significant in relation to air pollution by using of accurate quantumchemical and microscopic dynamics methods.1. The kinetics of the multiple-channel reaction CH-3OCl＋Clhas been investigatedover a wide temperature range200～3000K by dual-level direct dynamics method.The optimized geometries and frequencies of the stationary points are calculated atthe MP2/aug-cc-pvDz (Cl for aug-cc-pv(D+d)z) level,The minimum energy path iscalculated at the same level and further refined at the CCSD(T)/aug-cc-pvTz (Cl foraug-cc-pv(T+d)z)level.The rate constants are obtained by using the canonicalvariational transition state theory incorporating small-curvature tunneling correctionin the temperature range of200-3000K. The results show that anti-E2eliminationreaction channel is the dominant channel over the whole temperature range and thecorresponding rate constants present negative temperature dependence in the lowtemperature range, while positive temperature dependence in the high temperaturerange.In addition, we also investigated kinetic isotope effect of the reaction, byanalyzing the influence of different factors that affect the vibration contribution factoris the main factor. The three-parameter Arrhenius expression were also providedwithin200～3000K to facilitate future experimental studies.2. Microscopic mechanism of the reaction between N2O from the atmosphere and thenucleophilic butadiene anion has been investigated by using the second-orderperturbation theory calculation method and the rate-determining step of the mainchannel were calculated using the direct Kinetics method. In the study, presented threepossible reaction pathways in accordance with the mode of action of N2O:(1)terminal oxygen attack;(2) intermediate nitrogen attack;(3) nitrogen offensive end groups. The results show that: the main channel path mainly contained the oxygenatom transfer and the dissociation of formaldehyde that produced trans-C-3H3N2andCH2O. For the rate-determining step that is the oxygen atom transfer, we conducted aquantitative analysis calculation by using activation-strain model and conventionalTransition State Theory (TST) combine Zero Curvature Tunneling (ZCT) theory.Besides, as the isomer of the cyclobutene anion and the vinylcyclopropane carboxylicanion, we systematically compared the similarities and differences about the reactionsbetween three reactants and N2O.