(Pyrrole-2,5-diyl)-bis(nitronyl nitroxide) and-bis(iminonitroxide): Specific features of the synthesis, structure, and magnetic properties

Evgeny Tretyakov, Anastasia Tkacheva, Galina Romanenko, Artem Bogomyakov, Dmitri Stass, Alexander Maryasov, Ekaterina Zueva, Boris Trofimov, Victor Ovcharenko

Research output: Contribution to journalArticlepeer-review

Abstract

In contrast to diradicals connected by alternant hydrocarbons, only a few studies have addressed diradicals connected by nonalternant hydrocarbons and their heteroatom derivatives. Here, the synthesis, structure, and magnetic properties of pyrrole-2,5-diyl-linked bis(nitronyl nitroxide) and bis(iminonitroxide) diradicals are described. The diradicals show characteristic electron spin resonance spectra in dilute glassy solutions, from which conclusions about the presence of distinct conformations, their symmetry, and interspin distance were made. X-ray diffraction analysis of the diradicals revealed that paramagnetic moieties lie in the plane of the pyrrole ring, because of the formation of an intramolecular hydrogen bond, ONO . . . H−N, with O . . . H distances of 2.15-2.23 Å. The N-O groups participating in the formation of H-bonds have greater bond lengths (~1.29 Å) as compared with nonparticipating groups (~1.27 Å). The nitronyl nitroxide and iminonitroxide diradicals showed an intramolecular antiferromagnetic interaction, with J = −77.3 and −22.2 cm−1, respectively (H = −2JS1·S2).

Original languageEnglish
Article number1503
Number of pages13
JournalMolecules
Volume25
Issue number7
DOIs
Publication statusPublished - 26 Mar 2020

Keywords

  • Diradicals
  • Iminonitroxides
  • Magnetochemistry
  • Nitronyl nitroxides
  • Pyrrole derivatives
  • Quantum-chemical calculations
  • diradicals
  • nitronyl nitroxides
  • magnetochemistry
  • NITRONYL-NITROXIDE
  • STATE
  • DISJOINT
  • DIMERS
  • THIOPHENE
  • quantum-chemical calculations
  • DIRADICALS
  • pyrrole derivatives
  • iminonitroxides

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