Sites of protonation of N2-substituted N1,N1-dimethyl formamidines from regional reactivity indices

P. Pérez, R. Contreras, A. Aizman

Resultado de la investigación: Article

14 Citas (Scopus)

Resumen

N1,N1-dimethyl-N2-alkyl-formamidines and alkenyl, alkynyl and heteroalkyl derivatives present two potential sites for protonation reactions in the gas phase, namely, the amino (N1) and imino (N2) nitrogen atoms and eventually, a third potential protonation site at the N2 substituents. The protonation sites in polyfunctional molecules may be directly identified by using local reactivity indices. In this work, we present a theoretical analysis to predict protonation sites using the condensed or regional Fukui function formalism associated with a local hard and soft acids and bases (HSAB) principle. Our method correctly assesses the site of protonation in a wide series of N1,N1-dimethyl-N2-formamidines. The imino N2 site is predicted to be the preferred site for protonation, in close agreement with experimental data. Predicted proton affinities evaluated at the preferred (N2) site and obtained from HF/6-31G(d) calculations correlate well with the experimental values. The method is also tested against a short series of nicotinic acid derivatives that present closer values of proton affinity.

Idioma originalEnglish
Páginas (desde-hasta)267-273
Número de páginas7
PublicaciónJournal of Molecular Structure: THEOCHEM
Volumen493
N.º1-3
DOI
EstadoPublished - 15 dic 1999

Huella dactilar

Protonation
affinity
Protons
reactivity
nicotinic acid
protons
Niacin
nitrogen atoms
Nitrogen
Gases
vapor phases
formalism
acids
Acids
Derivatives
molecules
formamidine
Atoms
Molecules

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Citar esto

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abstract = "N1,N1-dimethyl-N2-alkyl-formamidines and alkenyl, alkynyl and heteroalkyl derivatives present two potential sites for protonation reactions in the gas phase, namely, the amino (N1) and imino (N2) nitrogen atoms and eventually, a third potential protonation site at the N2 substituents. The protonation sites in polyfunctional molecules may be directly identified by using local reactivity indices. In this work, we present a theoretical analysis to predict protonation sites using the condensed or regional Fukui function formalism associated with a local hard and soft acids and bases (HSAB) principle. Our method correctly assesses the site of protonation in a wide series of N1,N1-dimethyl-N2-formamidines. The imino N2 site is predicted to be the preferred site for protonation, in close agreement with experimental data. Predicted proton affinities evaluated at the preferred (N2) site and obtained from HF/6-31G(d) calculations correlate well with the experimental values. The method is also tested against a short series of nicotinic acid derivatives that present closer values of proton affinity.",
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Sites of protonation of N2-substituted N1,N1-dimethyl formamidines from regional reactivity indices. / Pérez, P.; Contreras, R.; Aizman, A.

En: Journal of Molecular Structure: THEOCHEM, Vol. 493, N.º 1-3, 15.12.1999, p. 267-273.

Resultado de la investigación: Article

TY - JOUR

T1 - Sites of protonation of N2-substituted N1,N1-dimethyl formamidines from regional reactivity indices

AU - Pérez, P.

AU - Contreras, R.

AU - Aizman, A.

PY - 1999/12/15

Y1 - 1999/12/15

N2 - N1,N1-dimethyl-N2-alkyl-formamidines and alkenyl, alkynyl and heteroalkyl derivatives present two potential sites for protonation reactions in the gas phase, namely, the amino (N1) and imino (N2) nitrogen atoms and eventually, a third potential protonation site at the N2 substituents. The protonation sites in polyfunctional molecules may be directly identified by using local reactivity indices. In this work, we present a theoretical analysis to predict protonation sites using the condensed or regional Fukui function formalism associated with a local hard and soft acids and bases (HSAB) principle. Our method correctly assesses the site of protonation in a wide series of N1,N1-dimethyl-N2-formamidines. The imino N2 site is predicted to be the preferred site for protonation, in close agreement with experimental data. Predicted proton affinities evaluated at the preferred (N2) site and obtained from HF/6-31G(d) calculations correlate well with the experimental values. The method is also tested against a short series of nicotinic acid derivatives that present closer values of proton affinity.

AB - N1,N1-dimethyl-N2-alkyl-formamidines and alkenyl, alkynyl and heteroalkyl derivatives present two potential sites for protonation reactions in the gas phase, namely, the amino (N1) and imino (N2) nitrogen atoms and eventually, a third potential protonation site at the N2 substituents. The protonation sites in polyfunctional molecules may be directly identified by using local reactivity indices. In this work, we present a theoretical analysis to predict protonation sites using the condensed or regional Fukui function formalism associated with a local hard and soft acids and bases (HSAB) principle. Our method correctly assesses the site of protonation in a wide series of N1,N1-dimethyl-N2-formamidines. The imino N2 site is predicted to be the preferred site for protonation, in close agreement with experimental data. Predicted proton affinities evaluated at the preferred (N2) site and obtained from HF/6-31G(d) calculations correlate well with the experimental values. The method is also tested against a short series of nicotinic acid derivatives that present closer values of proton affinity.

KW - Fukui function and protonation sites

KW - Gas-phase basicity

KW - N1,N1-dimethylformamidines

KW - Proton affinity

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