Electro-Optical, Electronic and Conformational Transitions of Interstellar Alkyl Molecules at Different Temperatures: An Ab-Initio Study

Abstract

In this paper, electronic structure of iso-propyl cyanide (i-C3H7CN), gauche-normal-propyl cyanide (g-n-C3H7CN) and anti-normal-propyl cyanide (a-n-C3H7CN) have been optimized using DFT-B3LYP/aug-cc-pVDZ method in neutral and anionic states. Electro-optical properties, HOMO, LUMO and MEP surfaces have been computed in order to check the optical behaviour and chemical reactivity of these interstellar molecules. The a-n-C3H7CN molecule exhibits better electro-optical behaviour than g-n-C3H7CN and iso-C3H7CN molecules. Global reactivity descriptors, adiabatic and vertical electron affinities of these straight and branched alkyl molecules have been investigated. They have negative electron affinities, which means they emit energy in the form of an anion. The distribution of the chemical bonding and electron lone pairs inside the molecules has been discussed using ELF map. Further, the formation of g-n-C3H7CN from i-C3H7CN, a-n-C3H7CN from i-C3H7CN and a-n-C3H7CN from g-n-C3H7CN has been studied using transition state study at temperatures 10K, 298.15K and 500K respectively. Mechanism of formation of g-n-C3H7CN and a-n-C3H7CN from i-C3H7CN at 10K, 298.15K and 500K temperatures along with their physico-chemical properties have been elucidated.