Synthesis, structure and properties of nitronyl nitroxide diradicals with fused-thiophene couplers

Synthesis, structure and properties of nitronyl nitroxide diradicals with fused-thiophene couplers Full article

Journal

Journal of Physical Organic Chemistry
ISSN: 0894-3230

Output data

Year: 2016, Volume: 29, Number: 12, Pages: 725-734 Pages count : 10 DOI: 10.1002/poc.3561

Tags

EPR spectroscopy; nitronyl nitroxides; planar singlet diradicals; X-ray diffraction

Authors

Tretyakov Evgeny ^1,2 , Okada Keiji ³ , Suzuki Shuichi ³ , Baumgarten Martin ⁴ , Romanenko Galina ² , Bogomyakov Artem ² , Ovcharenko Victor ²

Affiliations

1	(Данные Web of science) Russian Acad Sci, Vorozhtsov Inst Organ Chem, Ak Lavrentiev Ave 9, Novosibirsk 630090, Russia
2	(Данные Web of science) Russian Acad Sci, Int Tomog Ctr, 3a Ul Inst Skaya, Novosibirsk 630090, Russia
3	(Данные Web of science) Osaka City Univ, Grad Sch Sci, Dept Chem, Sumiyoshi Ku, Osaka 5588585, Japan
4	(Данные Web of science) Max Planck Inst Polymer Res, Ackermannweg 10, D-55128 Mainz, Germany

Functionalized diradicals are widely used in chemistry, physics, biology and material sciences because of their inherently high reactivity and magnetic activity, but the synthesis of planar diradical molecules is still a challenge. This paper describes the effective synthesis and properties of diradicals in which nitronyl nitroxide fragments and a fused-thiophene bridge are almost coplanar. The diradicals DR1, DR2, DR4 were prepared in high yield by palladium-catalyzed cross-coupling of the (nitronyl nitroxide-2-ide)(triphenylphosphin)gold complex with 2,5-diiodothieno[2,3-b]thiophene, 2,5-diiodothieno[3,2-b]thiophene or 2,6-diiododithieno[3,2-b:2,3-d]thiophene correspondingly. The torsion angles between planes of the nitronyl nitroxide fragments and fused-thiophene systems lie in the range 2.6-8.5 degrees. The planarity of DR2 and DR4 makes the Kekule-type coupler units effective bridges to transmit magnetic interactions by a spin polarization mechanism. According to the magnetic susceptibility measurements, supported by density functional theory calculations, the singlet-triplet energy splitting (2J/k(B)) is -130K for DR2 and close to -80K for DR4. The singlet diradicals DR2 and DR4 are stable and demonstrate two one-electron reversible electrochemical oxidation peaks and two-electron quasi-reversible reduction peaks resulting in the formation of the corresponding bis(oxoammonium) dication or bis(aminooxidanide) dianion. Copyright (c) 2016 John Wiley & Sons, Ltd.

Tretyakov E. , Okada K. , Suzuki S. , Baumgarten M. , Romanenko G. , Bogomyakov A. , Ovcharenko V.
Synthesis, structure and properties of nitronyl nitroxide diradicals with fused-thiophene couplers
Journal of Physical Organic Chemistry. 2016. V.29. N12. P.725-734. DOI: 10.1002/poc.3561 WOS Scopus РИНЦ

Published online:	Apr 8, 2016
Published print:	Dec 1, 2016

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