THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"

A series of N-methyl-2-R1,R2-5-R3,R4- 1,3-oxazines (where R are either H or p-nitro phenyl group and R3,4 = H or CH3- group) have been theoretically studied by ab initio methods in the frame of MO theory. Optimized geometries were obtained at HF and B3LYP/6-31G" levels, whereas energies were de...

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Autores principales:	CONTRERAS,J. GUILLERMO, HURTADO,S. MARCELA
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2009
Materias:	1,3-Oxazines Nitrogen Inversion Lone-Pair Inversion Barrier Substituents Effects
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000100023
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spelling	oai:scielo:S0717-970720090001000232009-05-12THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"CONTRERAS,J. GUILLERMOHURTADO,S. MARCELA 1,3-Oxazines Nitrogen Inversion Lone-Pair Inversion Barrier Substituents Effects A series of N-methyl-2-R1,R2-5-R3,R4- 1,3-oxazines (where R are either H or p-nitro phenyl group and R3,4 = H or CH3- group) have been theoretically studied by ab initio methods in the frame of MO theory. Optimized geometries were obtained at HF and B3LYP/6-31G" levels, whereas energies were derived at MP2 and B3LYP levels employing the same basis set. Geometries obtained at DFT level are needed to obtain consistent values and good correlations between the experimental and theoretical ¹H-NMR data. The nitrogen lone pair would be axial orientated in I and II, since the N-methyl group lies in the equatorial position in the gas phase, whereas in compounds III and IV the methyl axial conformers increase their concentration, implying that inversion of the nitrogen lone pair takes place in an appreciable extent. PCM method predicts that solvents (CCl4, CHCl3, CH2Cl2) produce a significant effect on conformers preference, but just a modest influence on the equilibrium geometries and ¹H-NMR properties.info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaJournal of the Chilean Chemical Society v.54 n.1 20092009-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000100023en10.4067/S0717-97072009000100023
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	1,3-Oxazines Nitrogen Inversion Lone-Pair Inversion Barrier Substituents Effects
spellingShingle	1,3-Oxazines Nitrogen Inversion Lone-Pair Inversion Barrier Substituents Effects CONTRERAS,J. GUILLERMO HURTADO,S. MARCELA THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
description	A series of N-methyl-2-R1,R2-5-R3,R4- 1,3-oxazines (where R are either H or p-nitro phenyl group and R3,4 = H or CH3- group) have been theoretically studied by ab initio methods in the frame of MO theory. Optimized geometries were obtained at HF and B3LYP/6-31G" levels, whereas energies were derived at MP2 and B3LYP levels employing the same basis set. Geometries obtained at DFT level are needed to obtain consistent values and good correlations between the experimental and theoretical ¹H-NMR data. The nitrogen lone pair would be axial orientated in I and II, since the N-methyl group lies in the equatorial position in the gas phase, whereas in compounds III and IV the methyl axial conformers increase their concentration, implying that inversion of the nitrogen lone pair takes place in an appreciable extent. PCM method predicts that solvents (CCl4, CHCl3, CH2Cl2) produce a significant effect on conformers preference, but just a modest influence on the equilibrium geometries and ¹H-NMR properties.
author	CONTRERAS,J. GUILLERMO HURTADO,S. MARCELA
author_facet	CONTRERAS,J. GUILLERMO HURTADO,S. MARCELA
author_sort	CONTRERAS,J. GUILLERMO
title	THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
title_short	THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
title_full	THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
title_fullStr	THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
title_full_unstemmed	THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"
title_sort	effect of c2 and c5 substitutions on the nitrogen lone pair inversion in 1,3-oxazines"
publisher	Sociedad Chilena de Química
publishDate	2009
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000100023
work_keys_str_mv	AT contrerasjguillermo theeffectofc2andc5substitutionsonthenitrogenlonepairinversionin13oxazines AT hurtadosmarcela theeffectofc2andc5substitutionsonthenitrogenlonepairinversionin13oxazines AT contrerasjguillermo effectofc2andc5substitutionsonthenitrogenlonepairinversionin13oxazines AT hurtadosmarcela effectofc2andc5substitutionsonthenitrogenlonepairinversionin13oxazines
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THE EFFECT OF C2 AND C5 SUBSTITUTIONS ON THE NITROGEN LONE PAIR INVERSION IN 1,3-OXAZINES"

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