ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

Agnie Mylona Kosmas, Aristeidis Ntivas, Stavroula Liaska, and Demetrios K. Papayannis

Department of Chemistry, University of Ioannina, Ioannina, 45 110 Greece

Abstract: The structural, energetic, and thermochemical properties of a number of halogenated nitromethanes, CH _n X_3−n NO₂, and the isomeric nitrites, CH _n X_3−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 _f^ℴ, at 298 K are calculated for all halogenated isomers.

Keywords: halogenated methyl nitrates – electronic structure methods – halogen induction effect – relative energy – enthalpy of formation

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-012-0243-2

Chemical Papers 66 (12) 1157–1165 (2012)