Evaluación in silico de los parámetros termodinámicos del complejo activado en reacciones ion-molécula y molécula-radical en el medio interestelar en un rango de (20 a 300) K.

Abstract

In this work, computational chemistry has been employed to study the formation of 2 molecules with prebiotic character in the interstellar medium (CD3 , CH3 , c-C3H2O). The search focuses on identifying reactions with the necessary characteristics for the formation of cyclopropenone and methyl free radical in the Sgr B2 molecular cloud. For this purpose, the principle of spontaneity and theoretical background were applied, which allowed reducing an initial set of 11 possible reactions to a subset of 5 chemical routes. Work was conducted using the Gaussian 09 program, applying collision theory, transition state theory (TST), molecular orbital theory, and density functional theory (DFT). Within the applied methodology, the M05-2X method and the 6-31+G* basis set were used. Through molecular study and optimization, structural properties (bond lengths and bond angles), free energies, enthalpies, and activation free energies were determined. Additionally, rate constants were calculated at temperatures from 20 to 300 K, along with tunnel effect and Eckhart potential for 3 of the 5 proposed reactions, finding activation energies of 21.778 kcal/mol for reaction 1: c-C3H2 + O2 -C3H2O + O, and rate constants for reaction 4: CH4 + OH -> CH3 + H2 -C3H2 + OH c-C3HOH + H, three transition states leading to the c-C3HOH isomer were calculated. The presented results are consistent with experimental and theoretical studies of the systems studied.