An investigation of the reaction of O with CH2F2 with ab initio molecular orbital calculations

Abstract

A selected ion flow tube (SIFT) study of the O- + CH2F2 reaction is reported which gives the following negatively charged products at 298 K: CF2 (37%), OH- (25%) and electrons (38%). Ab initio molecular orbital calculations are carried out at various levels of sophistication to investigate the reaction paths and the relative energies of the possible reaction channels.Both the reactant-like (O-.CH2F2) and product-like (H2O.CF- 2) ion–molecule intermediates are located. However, it is found that the OH-.CHF2 product-like intermediate is not a stationary point on the (P)UMP2/6-31 + + G** hypersurface. A proton abstraction from CHF2 by OH- gives the H2O.CF- 2 intermediate without a barrier, which in turn gives rise to the product channel H2O + CF- 2. Extensive transition state searches, followed by intrinsic reaction coordinate (irc) path calculations, locate a number of transition state structures and minima, but none of them is connected with any of the observed products. Nevertheless, one transition state ...