Molecular structure of 2,6-difluorobenzenamine and 2-fluorobenzenamine from gas-phase electron diffraction

Éva Csákvari, István Hargittai

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Abstract

The molecular structures of 2,6-difluorobenzenamine and 2-fluorobenzenamine have been investigated by gas-phase electron diffraction. The experimental data of the difluoro derivative are consistent with Cs point group the symmetry plane being perpendicular to the ring and bisecting the H-N-H angle. Considerable angular ring deformation has been found for both molecules, dominated by the presence of the F substituents and consistent with additivity of substituent impact. The structure for the monofluorine derivative, with no symmetry, is less precise than for the difluoro derivative. The ring angles at fluorine and NH2 are 123.6 ± 0.2° and 115.6 ± 0.4° for 2,6-difluorobenzenamine and 123.7 ± 0.8° and 117.6 ± 1.3° for 2-fluorobenzenamine. The C-F bonds are somewhat tilted toward the amino group, 2.1 ± 0.5° and 1.3 ± 0.6° in the difluoro and monofluoro derivatives, respectively. However, there is no other geometrical indication of intramolecular H bond in either molecule. Some further bond lengths (rg) and angles with estimated total errors for 2,6-difluorobenzenamine are as follows: N-H 1.009 ± 0.007 Å, (C-C)mean 1.391 ± 0.003 Å, F-C 1.356 ± 0.004 Å, C2C3C4 (γ) 118.8 ± 0.2°, C3C4C5 (δ) 119.7 ± 0.4°, dihedral angle HNH/ring 44 ± 6°. 2-Fluorobenzenamine: (C-C)mean 1.394 ± 0.003 Å, F-C 1.365 ± 0.008 Å, C1C6C5 (β′) 120.7 ± 0.9°, C2C3C4 (γ) 118.3 ± 0.6°, C4C5C6 (γ′) 120.5 ± 0.6°, C3C4C5 (δ) 119.2 ± 0.7°, dihedral angle HNH/ring 26 ± 12°.

Original languageEnglish
Pages (from-to)5837-5842
Number of pages6
JournalJournal of physical chemistry
Volume96
Issue number14
DOIs
Publication statusPublished - Jan 1 1992

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ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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