Theoretical Investigation For The Cycle Reaction Of Methane Oxidation Catalyzed By FeO⁺and The Reaction Of CH₄with NH₃Catalyzed By Pt⁺in The Gas Phase

It is a hot issue to the chemists that using transition metal atoms or ions and their oxidizedmolecules or ions activate small organic molecules not only experimental but theoretical studies.Many of these studies concentrated on the activate the C–H bond of hydrocarbons (CH4, C2H4,CH3OH…) and abatement some air pollutants (N2O，CO2，CO，NO2). For the transition metaloxides transition metals or participate in the reaction, because of there are not full of theexistence of electronic d orbitals in the transition metals, the chemical reaction do not obeythe law of conservation of "spin". Usually, more than one potential energy surface isinvolved in reaction process, and the reaction always proceeds on the low-energy potentialenergy surface (PES). This phenomenon is called “two-state reactivity (TSR)”.This issue according to the theory of two states reaction (TSR), using density functionaltheory (density functional, DFT), and corresponding calculation methods, such as group,used Gaussian03, Crossing2004, NBO5.0program, studied the FeO+catalytic CH4oxidationand the reaction of CH4with NH3catalyzed by Pt+.The paper consists of four chapters, Chapter1and Chapter2describe the progress andapplication of quantum chemistry as well as the development and the present situation ofTSR. At the same time, in order to provide reliable quantum chemistry theory basis andpractical basis for our study. We introduce basic theory of quantum chemistry, calculationmethods and the energetic span model."The gas phase FeO+catalytic methane oxidation "as the research object in the thirdchapter. For the FeO+(4Π+,6Σ+) catalytic methane oxidation that in quartet and sextet statespotential energy surface, we made a detailed research. First, through calculation, the reactionpotential energy surface is established, we found that the reaction is a two typical state, thereare6times potential energy surface crossing in the process of reaction. Through calculating the spin-orbit coupling (SOC), we discussed the situation of potential energy crossing andthe possibility of the spin flip. Then, through analyzed the reaction paths, we found thelowest energy path. Finally, The turnover frequency (TOF) in the catalytic cycles wascalculated by employing the energetic span model proposed by Kozuch. Moreover, therate-determining state of the entire reaction was determined.In the fourth chapter,"the cycle reaction of CH4and NH3catalyzed by Pt+" as theresearch system. Through calculations, we found this reaction is singlet state reaction, thephenomenon that the process of reaction potential energy surface crossing did not appear inthis reaction. In this chapter, we analyses why the reaction is singlet state and themechanism of different reaction path. The catalytic transformation frequency that is likely tobe the lowest energy path were calculated.