Molecular structure of nitrobenzene in the planar and orthogonal conformations - A concerted study by electron diffraction, X-ray crystallography, and molecular orbital calculations

Aldo Domenicano, György Schultz, I. Hargittai, Marcello Colapietro, Gustavo Portalone, Philip George, Charles W. Bock

Research output: Contribution to journalArticle

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Abstract

The molecular structure and ring distortions of nitrobenzene have been determined by gas-phase electron diffraction and ab initio molecular orbital (MO) calculations as well as from the structures of six derivatives studied by X-ray crystallography. The experimental value of the ring angle at the ipso position is α = 123.4 ± 0.3° in the free molecule; this is about 1.5° less than the hitherto reported values. Regression analysis of the ring angles in the six derivatives studied by X-ray crystallography yields α = 122.7(1)° for nitrobenzene in a crystalline environment. The small difference in the two values of a is interpreted as an effect of intermolecular interactions in the crystal. The value produced by the MO calculations, α = 122.3° at the 6-31G* (5 D) level, is smaller than either of the experimental results. As regards the ring angles at the meta and para positions, the three techniques of structure determination consistently indicate that these are larger than 120° by a few tenths of a degree. Other important geometrical parameters from the electron diffraction study are 〈rg(C-C)〉 = 1.399 ± 0.003 Å, rg(C-N) = 1.486 ± 0.004 Å, rg(N-O) = 1.223 ± 0.003 Å, and A sO-N-O = 125.3 ± 0.2°. X-ray diffraction experiments on 3,5-dimethyl-4-nitrobenzoic acid and 3,5-dimethylbenzoic acid and ab initio MO calculations provide solid evidence that the geometry of nitrobenzene is little affected when the nitrogroup is twisted by 90° out of the planar equilibrium conformation. This indicates that the extent of π-electron transfer from the benzene ring to the nitro group is small. The barrier to rotation is estimated to be 17 ± 4 kJ mol-1 from the electron diffraction data.

Original languageEnglish
Pages (from-to)107-122
Number of pages16
JournalStructural Chemistry
Volume1
Issue number1
DOIs
Publication statusPublished - Jan 1990

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Orbital calculations
nitrobenzenes
X ray crystallography
X Ray Crystallography
Molecular orbitals
Molecular Structure
Electron diffraction
Molecular structure
crystallography
Conformations
molecular orbitals
4-nitrobenzoic acid
molecular structure
electron diffraction
Electrons
rings
Derivatives
x rays
Benzene
Regression analysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Structural Biology

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Molecular structure of nitrobenzene in the planar and orthogonal conformations - A concerted study by electron diffraction, X-ray crystallography, and molecular orbital calculations. / Domenicano, Aldo; Schultz, György; Hargittai, I.; Colapietro, Marcello; Portalone, Gustavo; George, Philip; Bock, Charles W.

In: Structural Chemistry, Vol. 1, No. 1, 01.1990, p. 107-122.

Research output: Contribution to journalArticle

Domenicano, Aldo ; Schultz, György ; Hargittai, I. ; Colapietro, Marcello ; Portalone, Gustavo ; George, Philip ; Bock, Charles W. / Molecular structure of nitrobenzene in the planar and orthogonal conformations - A concerted study by electron diffraction, X-ray crystallography, and molecular orbital calculations. In: Structural Chemistry. 1990 ; Vol. 1, No. 1. pp. 107-122.
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abstract = "The molecular structure and ring distortions of nitrobenzene have been determined by gas-phase electron diffraction and ab initio molecular orbital (MO) calculations as well as from the structures of six derivatives studied by X-ray crystallography. The experimental value of the ring angle at the ipso position is α = 123.4 ± 0.3° in the free molecule; this is about 1.5° less than the hitherto reported values. Regression analysis of the ring angles in the six derivatives studied by X-ray crystallography yields α = 122.7(1)° for nitrobenzene in a crystalline environment. The small difference in the two values of a is interpreted as an effect of intermolecular interactions in the crystal. The value produced by the MO calculations, α = 122.3° at the 6-31G* (5 D) level, is smaller than either of the experimental results. As regards the ring angles at the meta and para positions, the three techniques of structure determination consistently indicate that these are larger than 120° by a few tenths of a degree. Other important geometrical parameters from the electron diffraction study are 〈rg(C-C)〉 = 1.399 ± 0.003 {\AA}, rg(C-N) = 1.486 ± 0.004 {\AA}, rg(N-O) = 1.223 ± 0.003 {\AA}, and A sO-N-O = 125.3 ± 0.2°. X-ray diffraction experiments on 3,5-dimethyl-4-nitrobenzoic acid and 3,5-dimethylbenzoic acid and ab initio MO calculations provide solid evidence that the geometry of nitrobenzene is little affected when the nitrogroup is twisted by 90° out of the planar equilibrium conformation. This indicates that the extent of π-electron transfer from the benzene ring to the nitro group is small. The barrier to rotation is estimated to be 17 ± 4 kJ mol-1 from the electron diffraction data.",
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T1 - Molecular structure of nitrobenzene in the planar and orthogonal conformations - A concerted study by electron diffraction, X-ray crystallography, and molecular orbital calculations

AU - Domenicano, Aldo

AU - Schultz, György

AU - Hargittai, I.

AU - Colapietro, Marcello

AU - Portalone, Gustavo

AU - George, Philip

AU - Bock, Charles W.

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N2 - The molecular structure and ring distortions of nitrobenzene have been determined by gas-phase electron diffraction and ab initio molecular orbital (MO) calculations as well as from the structures of six derivatives studied by X-ray crystallography. The experimental value of the ring angle at the ipso position is α = 123.4 ± 0.3° in the free molecule; this is about 1.5° less than the hitherto reported values. Regression analysis of the ring angles in the six derivatives studied by X-ray crystallography yields α = 122.7(1)° for nitrobenzene in a crystalline environment. The small difference in the two values of a is interpreted as an effect of intermolecular interactions in the crystal. The value produced by the MO calculations, α = 122.3° at the 6-31G* (5 D) level, is smaller than either of the experimental results. As regards the ring angles at the meta and para positions, the three techniques of structure determination consistently indicate that these are larger than 120° by a few tenths of a degree. Other important geometrical parameters from the electron diffraction study are 〈rg(C-C)〉 = 1.399 ± 0.003 Å, rg(C-N) = 1.486 ± 0.004 Å, rg(N-O) = 1.223 ± 0.003 Å, and A sO-N-O = 125.3 ± 0.2°. X-ray diffraction experiments on 3,5-dimethyl-4-nitrobenzoic acid and 3,5-dimethylbenzoic acid and ab initio MO calculations provide solid evidence that the geometry of nitrobenzene is little affected when the nitrogroup is twisted by 90° out of the planar equilibrium conformation. This indicates that the extent of π-electron transfer from the benzene ring to the nitro group is small. The barrier to rotation is estimated to be 17 ± 4 kJ mol-1 from the electron diffraction data.

AB - The molecular structure and ring distortions of nitrobenzene have been determined by gas-phase electron diffraction and ab initio molecular orbital (MO) calculations as well as from the structures of six derivatives studied by X-ray crystallography. The experimental value of the ring angle at the ipso position is α = 123.4 ± 0.3° in the free molecule; this is about 1.5° less than the hitherto reported values. Regression analysis of the ring angles in the six derivatives studied by X-ray crystallography yields α = 122.7(1)° for nitrobenzene in a crystalline environment. The small difference in the two values of a is interpreted as an effect of intermolecular interactions in the crystal. The value produced by the MO calculations, α = 122.3° at the 6-31G* (5 D) level, is smaller than either of the experimental results. As regards the ring angles at the meta and para positions, the three techniques of structure determination consistently indicate that these are larger than 120° by a few tenths of a degree. Other important geometrical parameters from the electron diffraction study are 〈rg(C-C)〉 = 1.399 ± 0.003 Å, rg(C-N) = 1.486 ± 0.004 Å, rg(N-O) = 1.223 ± 0.003 Å, and A sO-N-O = 125.3 ± 0.2°. X-ray diffraction experiments on 3,5-dimethyl-4-nitrobenzoic acid and 3,5-dimethylbenzoic acid and ab initio MO calculations provide solid evidence that the geometry of nitrobenzene is little affected when the nitrogroup is twisted by 90° out of the planar equilibrium conformation. This indicates that the extent of π-electron transfer from the benzene ring to the nitro group is small. The barrier to rotation is estimated to be 17 ± 4 kJ mol-1 from the electron diffraction data.

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