Experimental and theoretical investigations of the ion-neutral reaction of C2H2N+ with C2H6 and implications on chain elongation processes in Titan's atmosphere

In this study we report theoretical and experimental evidence for the formation of ionic products by the ion-neutral reaction of C2H2N+ with C2H6. Our investigations consist of laboratory measurements using a guided ion beam mass spectrometer together with complementary ab initio quantum chemical computations, at the MP2/6-311++G(d,p) level of theory, in order to elucidate the energetics and geometries of the intermediates and transition states that are involved in the production of the observed product ions. This study also provides insights on the isomeric nature of the observed product ions, their formation pathways together with collision energy and pressure dependences. The experimental data agrees well with the predictions of the ab initio calculations. Despite data provides evidence for the occurrence of C2H5 + as the most salient product ion, the production of CH3 +, C2H3 +, C3H5 +, C3H7 + and C2H4N+ is also evident. A reaction scheme was proposed to elucidate the mechanisms responsible for the formation of the observed product ions. These processes might be intermediate steps in the generation of long chain carbon and nitrogen-bearing compounds in Titan's ionosphere, the interstellar medium or circumstellar envelopes.