Molecular structure and conformational composition of 1-[(methylthio) methyl]-2-nitrobenzene (MTMNB)

A theoretical and experimental study

Olga V. Dorofeeva, Igor F. Shishkov, Lev V. Vilkov, I. Hargittai

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by electron diffraction at 130°C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified. Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter values (r a in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers are r(C-C) = 1.507(5), r(C-C)ring,av = 1.397(3), r(C-S)av = 1.814(4), r(C-N) = 1.495(4), r(N-O)av = 1.223(3), 〈(C-C-C)ring = 116.0-122.5, 〈C6-C4-C7 = 118.2(4), 〈C-C-S = 113.6(6), 〈C-S-C = 98.5(12), 〈N-C-C4 = 121.9(3), 〈(O-N-C)av = 116.8(3), 〈O-N-O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the rotation about C-N bond, φC-N, were found to be 30.5-36.5° for different conformers. As to internal rotation about C-C and C-S bonds, values of φC-C = 68-118° and φC-S = 66-71° were obtained for the three most stable conformers with gauche orientation with respect to these bonds.

Original languageEnglish
Pages (from-to)617-628
Number of pages12
JournalStructural Chemistry
Volume16
Issue number6
DOIs
Publication statusPublished - Dec 2005

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nitrobenzenes
Molecular Structure
Electron diffraction
Molecular structure
Theoretical Models
molecular structure
Electrons
Potential energy surfaces
Geometry
Vibrational spectra
electron diffraction
Chemical analysis
Density functional theory
Boltzmann distribution
rings
geometry
energy
potential energy
density functional theory
harmonics

Keywords

  • 1-[(Methylthio)methyl]-2-nitrobenzene
  • B3LYP/cc-pVTZ calculations
  • Conformational analysis
  • Gas electron diffraction

ASJC Scopus subject areas

  • Chemistry(all)
  • Structural Biology

Cite this

Molecular structure and conformational composition of 1-[(methylthio) methyl]-2-nitrobenzene (MTMNB) : A theoretical and experimental study. / Dorofeeva, Olga V.; Shishkov, Igor F.; Vilkov, Lev V.; Hargittai, I.

In: Structural Chemistry, Vol. 16, No. 6, 12.2005, p. 617-628.

Research output: Contribution to journalArticle

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abstract = "The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by electron diffraction at 130°C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified. Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter values (r a in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers are r(C-C) = 1.507(5), r(C-C)ring,av = 1.397(3), r(C-S)av = 1.814(4), r(C-N) = 1.495(4), r(N-O)av = 1.223(3), 〈(C-C-C)ring = 116.0-122.5, 〈C6-C4-C7 = 118.2(4), 〈C-C-S = 113.6(6), 〈C-S-C = 98.5(12), 〈N-C-C4 = 121.9(3), 〈(O-N-C)av = 116.8(3), 〈O-N-O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the rotation about C-N bond, φC-N, were found to be 30.5-36.5° for different conformers. As to internal rotation about C-C and C-S bonds, values of φC-C = 68-118° and φC-S = 66-71° were obtained for the three most stable conformers with gauche orientation with respect to these bonds.",
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T1 - Molecular structure and conformational composition of 1-[(methylthio) methyl]-2-nitrobenzene (MTMNB)

T2 - A theoretical and experimental study

AU - Dorofeeva, Olga V.

AU - Shishkov, Igor F.

AU - Vilkov, Lev V.

AU - Hargittai, I.

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N2 - The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by electron diffraction at 130°C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified. Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter values (r a in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers are r(C-C) = 1.507(5), r(C-C)ring,av = 1.397(3), r(C-S)av = 1.814(4), r(C-N) = 1.495(4), r(N-O)av = 1.223(3), 〈(C-C-C)ring = 116.0-122.5, 〈C6-C4-C7 = 118.2(4), 〈C-C-S = 113.6(6), 〈C-S-C = 98.5(12), 〈N-C-C4 = 121.9(3), 〈(O-N-C)av = 116.8(3), 〈O-N-O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the rotation about C-N bond, φC-N, were found to be 30.5-36.5° for different conformers. As to internal rotation about C-C and C-S bonds, values of φC-C = 68-118° and φC-S = 66-71° were obtained for the three most stable conformers with gauche orientation with respect to these bonds.

AB - The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by electron diffraction at 130°C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified. Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter values (r a in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers are r(C-C) = 1.507(5), r(C-C)ring,av = 1.397(3), r(C-S)av = 1.814(4), r(C-N) = 1.495(4), r(N-O)av = 1.223(3), 〈(C-C-C)ring = 116.0-122.5, 〈C6-C4-C7 = 118.2(4), 〈C-C-S = 113.6(6), 〈C-S-C = 98.5(12), 〈N-C-C4 = 121.9(3), 〈(O-N-C)av = 116.8(3), 〈O-N-O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the rotation about C-N bond, φC-N, were found to be 30.5-36.5° for different conformers. As to internal rotation about C-C and C-S bonds, values of φC-C = 68-118° and φC-S = 66-71° were obtained for the three most stable conformers with gauche orientation with respect to these bonds.

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KW - Conformational analysis

KW - Gas electron diffraction

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