Rate Constants for the Reactions of Chlorine Atoms with Deuterated Methanes: Experiment and Theory

Abstract

Long-path FTIR spectroscopy and ab initio calculations combined with conventional transition state theory were used to study the kinetics of the reactions of Cl atoms with deuterated methanes. The following experimental relative rate constants for the reaction of Cl atoms at 298 ± 5 K and 760 ± 5 Torr were determined: CH3D, (6.5 ± 0.5) × 10-14; CH2D2, (4.2 ± 0.5) × 10-14; CHD3, (1.9 ± 0.3) × 10-14; CD4, (5.4 ± 0.4) × 10-15. All experimental and theoretical rate constants are in units of cm3 molecule-1 s-1 and are relative to the 1.0 × 10-13 cm3 molecule-1 s-1 rate constant for the reaction of Cl with CH4. All experimental uncertainty limits are 2σ. The geometries, energies, and frequencies of the reactants, products, and transition states were calculated at the level of the second-order Moller−Plesset approximation using a 6-311++G(2d,2p) basis set. The following theoretical relative rate constants were calculated at 298 K using conventional transition state theory combined with an Eckart one-dimensional...