Ferro- and antiferromagnetic interactions in polymeric and molecular complexes of Cu(hfac) 2 with 1-oxoazin-2-yl-substituted nitronyl nitroxides

• Published in: Polyhedron 2011-03, Vol.30 (4), p.647-653
• Main Authors: Chupakhin, Oleg N., Tretyakov, Evgeny V., Utepova, Irina A., Varaksin, Mikhail V., Romanenko, Galina V., Bogomyakov, Artem S., Veber, Sergey L., Ovcharenko, Victor I.
• Format: Article
• Language: English
• Subjects: Azine- N-oxides; Copper complexes; Nitronyl nitroxides
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2010.11.029

Cu(hfac) 2 complexes with a new group of nitronyl nitroxides bearing different azine- N-oxide substituents at position 2 of the 2-imidazoline ring were prepared and characterized by squid magnetometry and X-ray diffraction techniques. Among the structural peculiarities are the formation of 7-membered metallocycles and a rare structural topology of the polymer chain. [Display omitted] ► Heterospin complexes with nitronyl nitroxides bearing N-oxoazines. ► 7-Membered metallocycles. ► A rare structural topology of the heterospin polymer chain. ► Ferro- and antiferromagnetic interactions. Solid heterospin compounds based on Cu(hfac) 2 complexes with a new group of nitronyl nitroxides bearing different azine- N-oxide substituents at position 2 of the 2-imidazoline ring (L n ) were studied. The major factor responsible for the change in the magnetic characteristics of the [Cu(hfac) 2L 1] complex with triazine nitronyl nitroxide with temperature was shown to be the specific pairwise packing of heterospin molecules with the dominant antiferromagnetic exchange between the radical fragments of adjacent molecules. For complexes of Cu(hfac) 2 with 1-oxoazin-2-yl-substituted nitronyl nitroxides L 2 and L 4, 7-membered metallocycles were obtained, although they form rarely. It was shown that polymer chains formed in the solid complex with spin-labeled pyrazine- N-oxide [(Cu(hfac) 2) 3(L 3) 2] due to the cross-linking of {(Cu(hfac) 2) 2(L 3) 2} binuclear fragments via the bridging [Cu(hfac) 2].