化学反应机理基础.ppt

The 11th National Conference of Quantum Chemistry * Theoretical study of the chemical reaction mechanism The 11th National Conference of Quantum Chemistry JIANG YaJun Potential energy surface Single-state reactivity Two-state reactivity Content 1. Potential energy surface AB+C→[A‥B‥C] ≠ → A+BC TS2 458.6i Gaussian 03 Keywords: Optimizing transition states Opt=TS Opt=QST2 Opt=QST3 Calculate the frequencies Freq Reaction path following IRC How to use Gaussian03 package search TS? TS1 371.1i CF2COO CF2COO →TS2 → CF2O+CO TS2 2 Single-state reactivity The description of chemical reactivity is based on the paradigm of spin conservation, namely that the rate-determining step proceed on surfaces with uniform spin multiplicity. 2.1 Reduction of N2O by CO: O-Atom Transport Catalysis by Fe+ (J. Am. Chem. Soc. 2005, 127, 3545.) M=Fe Methods: B3LYP/6-311+G(d) 2.2 CO oxidation mechanism by Au3+/0/- (J. Phys. Chem. C 2009, 113, 18032.) Which effect is important for catalytic activity of gold cluster during CO oxidation ? Charge state or Size ？ Au3+ Au3 Au3- Methods: PW91/6-311+G(d)-LANL2DZ Au3+ All energies are given in kcal/mol relative to the energies of the reactants. The golden, gray, and red balls denote Au, C, and O atoms, respectively. Au30 All energies are given in kcal/mol relative to the energies of the reactants. The golden, gray, and red balls denote Au, C, and O atoms, respectively. Au3- All energies are given in kcal/mol relative to the energies of the reactants. The golden, gray, and red balls denote Au, C, and O atoms, respectively. The calculated results indicates that the charge state of Au3 cluster has a substantial effect on the elementary mechanism, but plays a less important role for its catalytic activity toward CO oxidation. The size of gold cluster is important ! Science 2008, 321,1331. J. Am. Chem. Soc. 2009, 131, 538. 3 Two-state reactivity Transition Metals: Spin forbidden reactions are not forbidden Classical Concept: Different spin potential