A Weakly Antiferromagnetically Coupled Biradical Combining Verdazyl with Nitronylnitroxide Units.

Authors :: Petunin PV
Rybalova TV
Trusova ME
Uvarov MN
Kazantsev MS
Mostovich EA
Postulka L
Eibisch P
Wolf B
Lang M
Postnikov PS
Baumgarten M
Source :: ChemPlusChem [Chempluschem] 2020 Jan; Vol. 85 (1), pp. 159-162. Date of Electronic Publication: 2020 Jan 14.
Publication Year :: 2020
Abstract: An antiferromagnetically (AFM) coupled biradical based on oxoverdazyl and nitronylnitroxide was synthesized in 46 % yield using Sonogashira coupling. The obtained heterobiradical evidenced distinct properties of both radical entities in solution. Depending on the solvent, the prepared biradical crystallized in two different forms. SQUID magnetization measurements on Form II showed coupling constants J <subscript>intraII</subscript> /k <subscript>B</subscript> =-2.1 K and zJ <subscript>interII</subscript> /k <subscript>B</subscript> =-11.5 K. Consequently, total intermolecular exchange interactions are five times larger than the intramolecular ones. Further, DFT calculations explained this phenomenon and indicated the advantage of Form I for further in-depth investigations.<br /> (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

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