Kinetics and mechanisms of the reactions of CH and CD with H2S and D2S

The rate constants for the CH+H2S, CD+H2S, CH+D2S and CD+D2S reactions at 295 K were, respectively, measured to be (3.2±0.8)x10-10, (2.5±0.4)x10-10, (2.9±0.8)x10-10 and (2.6±0.6)x10-10 cm3 molecule-1 s-1 by using a laser-induced fluorescence technique. The rate constants were close to each other among the four isotopomer reactions; i.e., the corresponding kinetic isotope effects were found to be very small. The potential energy surface for this reaction was studied by using the ab initio molecular orbital theory. The MP4/cc-pVTZ//MP2/cc-pVDZ calculations suggest that the reaction proceeds mainly via the CH addition to the S atom in H2S with no barrier. The reaction was shown to have several possible products. RRKM calculations suggested that the main product channel is CH2S+H. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)