Electronic structure and aromaticity of azaphospholes

L. Nyulászi, T. Veszprémi, József Réffy, Bernd Burkhardt, Manfred Regitz

Research output: Contribution to journalArticle

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Abstract

The electronic structure of 1,3-azaphospholes, 1,2,4-diazaphospholes, and 1,2,3,4-triazaphospholes has been investigated by means of ab initio quantum chemical calculations and He I ultraviolet photoelectron spectroscopy. According to the 4-31G(*) geometry optimized calculations, the total energy of the tautomers containing σ23hosphorus is significantly higher (by 25-35 kcal/mol) than the total energy of those containing σ23-phosphorus. The aromatic stabilization - as measured by the heats of bond separation reactions - changes in a similar way. The investigation of the calculated optimized geometries revealed that the rings containing σ23-phosphorus can be characterized by bond lengths between those of isolated single and double bonds. In the case of the tautomers containing σ23-phosphorus, however, C-P (N-P) bond lengths are much closer to the single-bond value, indicating that conjugation is in force only on the rest of the molecule. In order to assess the conjugative interaction between the C=P moiety and the rest of the molecule, ring fragmentation reactions have been investigated. The heats of these reactions indicate that the conjugation of the P=C moiety (and thus the aromatic stability) increases with the increasing number of nitrogen atoms in the ring. The photoelectron spectra of the investigated compounds are in accordance with the electronic structure of the compounds containing σ23-phosphorus. Ionization energies when the electron was removed from π-orbitals are similar to those of the corresponding azoles.

Original languageEnglish
Pages (from-to)9080-9084
Number of pages5
JournalJournal of the American Chemical Society
Volume114
Issue number23
Publication statusPublished - 1992

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Phosphorus
Electronic structure
Bond length
Hot Temperature
Ultraviolet photoelectron spectroscopy
Photoelectron Spectroscopy
Azoles
Molecules
Geometry
Ionization potential
Photoelectrons
Nitrogen
Stabilization
Electrons
Atoms
single bond

ASJC Scopus subject areas

  • Chemistry(all)

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Electronic structure and aromaticity of azaphospholes. / Nyulászi, L.; Veszprémi, T.; Réffy, József; Burkhardt, Bernd; Regitz, Manfred.

In: Journal of the American Chemical Society, Vol. 114, No. 23, 1992, p. 9080-9084.

Research output: Contribution to journalArticle

Nyulászi, L, Veszprémi, T, Réffy, J, Burkhardt, B & Regitz, M 1992, 'Electronic structure and aromaticity of azaphospholes', Journal of the American Chemical Society, vol. 114, no. 23, pp. 9080-9084.
Nyulászi, L. ; Veszprémi, T. ; Réffy, József ; Burkhardt, Bernd ; Regitz, Manfred. / Electronic structure and aromaticity of azaphospholes. In: Journal of the American Chemical Society. 1992 ; Vol. 114, No. 23. pp. 9080-9084.
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