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Author(s): Jose R B Gomes
Emanuel A Sousa
Jorge M Goncalves
Luis Gales
Ana M Damas
Paula Gomes
Siddharth Pandey
William E Acree
Maria D M C Ribeiro da Silva
Title: Energetic and structural characterization of 2-R-3-methylquinoxaline-1,4-dioxides (R = benzoyl or tert-butoxycarbonyl): experimental and computational studies
Issue Date: 2007
Abstract: The gaseous standard molar enthalpies of formation of two 2-R-3-methylquinoxaline-1,4-dioxides (R = benzoyl or tert-butoxycarbonyl), at T = 298.15 K, were derived using the values for the enthalpies of formation of the compounds in the condensed phase, measured by static bomb combustion calorimetry, and for the enthalpies of sublimation, measured by Knudsen effusion, using a quartz crystal oscillator. The three dimensional structure of 2-tert-butoxycarbonyl-3-methylquinoxaline-1,4-dioxide has been obtained by X-ray crystallography showing that the two N-O bond lengths in this compound are identical. The experimentally determined geometry in the crystal is similar to that obtained in the gas-phase after computations performed at the B3LYP/6-311 + G(2d,2p) level of theory. The experimental and computational results reported allow to extend the discussion about the influence of the molecular structure on the dissociation enthalpy of the N-O bonds for quinoxaline 1,4-dioxide derivatives. As found previously, similar N-O bond lengths in quinoxaline-1,4-dioxide compounds are not linked with N-O bonds having the same strength. Copyright (c) 2007 John Wiley & Sons, Ltd.
Subject: Química
Chemical sciences
Scientific areas: Ciências exactas e naturais::Química
Natural sciences::Chemical sciences
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:FCUP - Artigo em Revista Científica Internacional
ICBAS - Artigo em Revista Científica Internacional

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