Intramolecular hydrogen bonding and molecular structure of 2-iminomethyl-phenol and molecular structure of iminomethyl-benzene from ab initio MO calculations

Konstantin B. Borisenko, István Hargittai

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Abstract

Ab initio calculations, including electron correlation (MP2), have been performed for iminomethyl-benzene and 2-imino-methyl-phenol. They indicate the existence of two (syn and anti) stable conformers of 2-iminomethyl-phenol. The principal syn conformer is characterized by considerable hydrogen bonding between the iminomethyl and hydroxy groups, accompanied by pronounced structural changes in the rest of the molecule, as compared with phenol and iminomethyl-benzene calculated at the same theoretical level. These structural changes are consistent with the notion of resonance-assisted hydrogen bonding, also observed in a series of nitrophenols and similar molecules. The anti conformer of 2-iminomethyl-phenol has 41.8 kJ mol-1 higher energy than the syn conformer. The internal rotation of iminomethyl group in 2-iminomethyl-phenol is hindered by a considerably higher barrier, 55.9 kJ mol-1, due to intramolecular hydrogen bond formation, than that in iminomethyl-benzene, 27.6 kJ mol-1, according to the calculations at the HF/6-31G* level. The amino tautomer form of 2-iminomethyl-phenol has 25.0 kJ mol-1 (HF/6-31G*) or 30.6 kJ mol-1 (MP2(FC)/6-31G*) higher energy than the imino form. The energy of the structural changes as compared to iminomethyl-benzene and phenol and the energy of the intramolecular hydrogen bond formation in 2-iminomethyl-phenol was estimated to be -28.8 kJ mol-1 at the HF/6-31G* level and -36.8 kJ mol-1 at the MP2(FC)/6-31G* level of theory.

Original languageEnglish
Pages (from-to)107-113
Number of pages7
JournalJournal of Molecular Structure: THEOCHEM
Volume388
Issue number1-3
Publication statusPublished - Dec 11 1996

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Keywords

  • 2-Iminomethyl-phenol
  • Ab initio MO calculations
  • Iminomethyl-benzene
  • Intramolecular hydrogen bonding
  • Molecular structure

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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