The magnetic behavior of this compound indicated the presence of competing short range ferromagnetic and antiferromagnetic interactions. In order to explain fully the magnetic behavior of this compound, the knowledge of the crystalline structure is necessary and new efforts to obtain single crystals are in progress. Carlos B. We also acknowledge Dr. Crystallographic data excluding structure factors for the structure in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication No.
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CCDC Copies of the data can be obtained, free of charge, via www. Gatteschi, D. Figuerola, A. Akhriff, Y. Amabilino, D. Miller, J. KGaA: Weinheim; , ch. Kinoshita, M. Caneschi A. Caneschi, A. Kahn, O. Stumpf, H.
Nitroxide Radicals and Nitroxide Based High-Spin Systems
Kalisz, M. Ulman, E. C , 24 , Vaz, M. Oxford Cryosystems Oxford Cryosystems, Oxford, United Kingdom. Sheldrick, G. Johnson, C. Colacio, E. Dalton Trans. Cador, O. Berliner, L. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Services on Demand Journal. Introduction The synthesis of molecule-based magnetic materials has been the object of increasing interest in the last years.
Experimental Reagents All chemicals were purchased from Fluka and Aldrich and used without further purification. Spectroscopic measurements Infrared spectra were measured over the region cm -1 with a Nicolet Magna FT-IR instrument, with 4 cm -1 resolution. Elemental analysis Carbon, nitrogen and hydrogen contents were determined on a PerkinElmer apparatus.
Synthesis of the NBu 4 4 [Cu 2 bopba ] 1 and the nitronyl nitroxide radical precursors The tetraethyl ester bis- o -phenylenebis oxamate H 4 Et 4 bopba was synthesized following the synthetic method used to prepare H 2 Et 2 opba 12 where H 2 Et 2 opba is ortho -phenylenebis oxamate , with an increase of two hours in the reaction time.
Magnetic measurements Variable-temperature magnetic susceptibility and isothermal magnetization measurements were performed on polycrystalline samples in the temperature range 2. Results and Discussion Description of the structure of the NBu 4 4 [Cu 2 bopba ] complex The NBu 4 4 [Cu 2 bopba ] structure was solved by direct methods in the non-centrosymmetric space group P2 1 using the Shelxs program. In , the octamethyl derivative of benzobisoxazine nitroxide diradical was reported to slowly decompose in solution by Rassat and Sieveking, thus its magnetic characterization was incomplete.
Intrigued by these results, we set out to investigate further magnetic properties of the diradical and to probe the effect of steric hindrance on stability and magnetic properties of annelated diradicals. We were able to optimize the synthesis and obtained the diradical both in good yield and with high purity. We found that the nitroxide diradical was stable in solution and in solid state. To probe the steric effects, we prepared the diradical in which all ortho and para positions of the m -phenylene are sterically shielded. We found that both nitroxide diradicals have robust triplet ground states with strong ferromagnetic coupling and good stability at ambient conditions.
The aim is to carried out detailed study on the finding, which we reported earlier Chem. Preparation of a cyclophane nitroxide diradical diazacyclophane with two ECPs is in progress. W e have prepared stable calixarene nitroxide raradicals with fixed cone and 1,3 alternate conformations. The nitroxide diradical and tetraradical with fixed cone conformation were reported in JACS , , , In the solid state, dimerization of one diagonal pair of nitroxides leads to a pinched cone conformation [ X-ray structure ].
Such intramolecular dimers of stable di- and polyradicals, with conformationally restricted macrocyclic backbone, may provide novel antiferromagnetic coupling units aCUs , which are essential for effective approaches to polymer-based organic magnets. W e prepared the calixarene nitroxide radicals with 1,3 alternate conformations and reinvestigated magnetic properties of the nitroxide radicals with fixed cone conformation JACS , , , The 1,3-alternate nitroxide diradical and tetraradical provide unique polyradical scaffolds for dissection of the through-bond and through-space intramolecular exchange couplings.
Tamura, D. Hosokoshi, N. Iwasawa, K. Nozawa, M. Kinoshita, H. Sawa and R. Kato Mol.
Sawa, R. Kato, Y. Fujiwara and Y. Ueda to be published in J. Kato to be published in J. Hernandez, M. Mas, E. Molins, C. Rovira and J. Veciana Angew. Sugano, T. Goto and M. Hosokoshi, D. Iwasawa, H.
Kato and M. Shiomi, N. Aruga Katori and T. Goto to be published in Physica B. Nozawa, S. Suzuki, M. Kato to be published in Synth. Nakamura, M. Matsumoto and Y. Sugano, M. Tamura, T. Goto, R. Kato, M. Kinoshita, Y. Sakai, Y. Ohashi, M. Kurmoo and P.
Day Mol. Nagashima, M. Matsumoto, Y. Kawabata and Y. Nagashima, T. Okuno, A. Yamaguchi, M. Hasegawa, T. Maruyama and N. Wada Phys. B 49 Pratt, R. Valladas, J.
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Index of series transporter
Fujioka and Y. Sawaki J. Izuoka, M. Fukuda, T. Sakai and S. Bandow Chem. Fukuda and T.
Sugawara Mol. Dulong and J. Kim Angew. Tamura, H. Shiomi, H. Aruga-Katori, T. Goto, H. Goto, A. Hayashi, Y. Ueda, H. Haldane Phys. A 93 Chiarelli, M. Novek, A. Rassat and J. Tholence Nature Nogami, K. Tomioka, T. Ishida, H. Yoshikawa, M. Yasui, F. Iwasaki, H. Iwamura, N. Ishikawa Chem. Nogami private communication. Tsuboi, T. Nogami, H. Sugimoto private communication. Mukai, K. Nedachi, J. Jamali and N. Achiwa Chem.