Unimolecular and bimolecular reactions in the C4H6+⋅ system: Experiment and theory

New experimental data on the metastable reactions of C4H6+⋅ are presented. The bimolecular reactions between C2H2+⋅ and C2H4 and between C2H4+⋅ and C2H2 have been reinvestigated using a tandem ICR. Total rate constants and branching ratios were measured and isotopic scrambling investigated using deuterium labeling. The experimental data reported here and the PIPECO data of Werner and Baer [J. Chem. Phys. 62, 2900 (1975)] are compared with the predictions of the transition state switching model. Good agreement was found between the predictions of the model and the experimental data. The branching ratios were found to be strong functions of both energy and angular momentum. In the bimolecular reaction between C2H2+ and C2H4 charge transfer appears to occur predominently via a loosely bound intermediate which only samples a small volume of the available C4H+⋅6 phase space.