Computational Study of the Mechanism of the Oxidation of Hydrazine / Hydrazinium Ion by Iodine in the Gas Phase

Abstract

The reaction mechanisms of the oxidation of hydrazine / hydrazinium ion by iodine have been studied using 6311+G** basis set of the density functional theory (DFT) method at the B3LYP level of computation. The study shows that the oxidation reactions can proceed via four independent routes or pathways that can be separately monitored. Two of the proposed pathways involved a two-step reaction mechanism each, in which two transition states were produced while each of the other two routes involved three-step reaction mechanism in which three activated complexes were produced. The results obtained were based on the analyses of the computational energetics of the optimized reactants, intermediates, transition states and products of the reaction of iodine with hydrazine / hydrazinium ion. The study showed that all the four proposed routes were possible by comparing the enthalpies of reactions of the four proposed pathways as well as the activation barriers of the respective rate determining steps which were found to be reasonably acceptable. Rate laws, which were consistent with the written mechanisms, were also derived for each of the proposed mechanisms.

Roles of Hydrogen, Halogen Bonding and Aromatic Stacking in a Series of Isophthalamides

“…The X-DIP molecules were modelled in gas phase using DFT (B3LYP/6-311++G**) methods [30,31] and only the I-DIP molecule was optimised by several semi-empirical methods (AM1, PM3, MNDO), then optimised by the (B3LYP/3-21G) method due to the difficulty in using (B3LYP/6-311++G**) for iodo-containing molecules [30,31,55,56]. The main geometric parameters are the (i) α-dihedral C12-C11-C1=O1 angle, (ii) β-dihedral C1-N1-C21-C26 and (iii) γ or amide dihedral angle H1-N1-C1=O1.…”