Theoretical enthalpies of formation and structural characterisation of halogenated nitromethanes and isomeric halomethyl nitrites

Abstract

AbstractThe structural, energetic, and thermochemical properties of a number of halogenated nitromethanes, CHnX3−n NO2, and the isomeric nitrites, CHnX3−n ONO, are investigated, using theoretical ab initio and density functional theory (DFT) electronic structure methods. Analysis of the results and comparison with the maternal species, nitromethane, CH3NO2, and methyl nitrite, CH3ONO, reveal strong dependence of the molecular properties on the halogen induction effect. Opposite trends are obtained in the C—N and C—O bond dissociation energies (BDE) upon halogenation and higher stabilities are calculated for the trans-nitrite isomers, in contrast with the plain alkyl families where the nitroalkanes are the most stable species. Formation enthalpies, ΔH fℴ, at 298 K are calculated for all halogenated isomers.