Ab initio study of the OH + CH 2 O reaction: The effect of the OH··OCH 2 complex on the H‐abstraction kinetics

Kinetics for the reaction of OH radical with CH 2 O has been studied by single‐point calculations at the CCSD(T)/6‐311+G(3 df , 2 p ) level based on the geometries optimized at the B3LYP/6‐311+G(3 df , 2 p ) and CCSD/6‐311++G( d , p ) levels. The rate constant for the reaction has been computed in the temperature range 200–3000 K by variational transition state theory including the significant effect of the multiple reflections above the OH··OCH 2 complex. The predicted results can be represented by the expressions k 1 = 2.45 × 10 ‐21 T 2.98 exp (1750/ T ) cm 3 mol −1 s −1 (200–400 K) and 3.22 × 10 ‐18 T 2.11 exp(849/ T ) cm 3 mol −1 s −1 (400–3000 K) for the H‐abstraction process and k 2 = 1.05 × 10 ‐17 T 1.63 exp(−2156/ T ) cm 3 mol −1 s −1 in the temperature range of 200–3000 K for the HO‐addition process producing the OCH 2 OH radical. The predicted total rate constants ( k 1 + k 2 ) can reproduce closely the recommended kinetic data for OH + CH 2 O over the entire range of temperature studied. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 322–326, 2006