(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

Результат исследования: Научные публикации в периодических изданияхстатья

Аннотация

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).

Язык оригиналаанглийский
Номер статьи1503
Число страниц13
ЖурналMolecules
Том25
Номер выпуска7
DOI
СостояниеОпубликовано - 26 мар 2020

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