Magnetic properties of phenol-substituted nitronyl nitroxide biradicals as building blocks of organic salt ferrimagnets

(a) M. Tamura, Y. Nakazawa, D. Shiomi, K. Nozawa, Y. Hosokoshi, M. Ishikawa, M. Takahashi, M. Kinoshita, Chem. Phys. Lett. 186 (1991) 411. (b) Y. Nakazawa, M. Tamura, N. Shirakawa, D. Shiomi, M. Takahashi, M. Kinoshita, Phys. Rev. B 46 (1992) 8906. For reviews of molecule-based magnetics, see (a) D. Gatteschi, O. Kahn, J.S. Miller, F. Palacio (Eds.), Molecular Magnetic Materials, Kluwer Academic, Dordrecht, 1991. (b) H. Iwamura, J.S. Miller (Eds.), Mol. Cryst. Liq. Cryst. 232 (1993). (c) J.S. Miller, A.J Epstein (Eds.), Mol. Cryst. Liq. Cryst. 271 (1995). (d) K. Itoh, J.S. Miller, T. Takui (Eds.), Mol. Cryst. Liq. Cryst. 305 (1997). (e) O. Kahn (Ed.), Mol. Cryst. Liq. Cryst. 334 (1999). (f) P.M. Lahti (Ed.), Magnetic Properties of Organic Materials, Marcel Dekker, New York, 1999. In this paper, we mean by ‘ferrimagnetic’ that the intermolecular interaction between neighboring molecules with different spin quantum numbers is primarily antiferromagnetic in a bipartite lattice but an antiparallel spin alignment between the molecules with different magnetic moments gives net magnetization arising from the differing moments ordered in the sublattices. Buchachenko, 1979, Dokl. Akad. Nauk. Eng. Ed., 244, 107 For example, see (a) O. Kahn, Y. Pei, M. Verdaguer, J. P. Renard, J. Sletten, J. Am. Chem. Soc. 110 (1988) 782. (b) A. Caneschi, D. Gatteschi, J. P. Renard, P. Rey, R. Sessoli, Inorg. Chem. 28 (1989) 1976. (c) H. O. Stumpf, L. Ouahab, Y. Pei, P. Bergerat, O. Kahn, J. Am. Chem. Soc. 116 (1994) 3866. (d) M. Hagiwara, K. Minami, Y. Narumi, K. Tatani, K. Kindo, J. Phys. Soc. Jpn. 67 (1998) 2209. (e) M. Hagiwara Y. Narumi, K. Minami, K. Tatani, K. Kindo, J. Phys. Soc. Jpn. 68 (1999) 2214. Izuoka, 1994, J. Am. Chem. Soc., 116, 2609, 10.1021/ja00085a047 Shiomi, 1997, J. Phys. Chem. Sect. B, 101, 3342, 10.1021/jp970111t Nishizawa, 2000, J. Phys. Chem. Sect. B, 104, 503, 10.1021/jp992980j Shiomi, 2000, J. Phys. Chem. Sect. B, 104, 1961, 10.1021/jp993929i Desiraju, 1989 (a) D. Shiomi, K. Ito, M. Nishizawa, K. Sato, T. Takui, K. Itoh, Synth. Met. 103 (1999) 2271. (b) D. Shiomi, K. Ito, M. Nishizawa, S. Hase K. Sato, T. Takui, K. Itoh, Mol. Cryst. Liq. Cryst. 334 (1999) 99. Organic salts consisting of S=1/2 radicals have been reported: (a) K. Awaga, A. Yamaguchi, T. Okuno, T. Inabe, T. Nakamura, M. Matsumoto, Y. Maruyama, J. Mater. Chem. 4 (1994) 1377. (b) T. Otsuka, T. Okuno, M. Ohkawa, T. Inabe, K. Awaga, Mol. Cryst. Liq. Cryst. 306 (1997) 285. S. Hase, D. Shiomi, K. Sato, T. Takui, J. Mater. Chem. 11 (2001) 756. Bae, 1999, Bull. Magn. Reson., 19, 39 Kamiyama, 2000, Appl. Magn. Reson., 19, 45, 10.1007/BF03162260 (a) M. Dvolaitzky, R. Chiarelli, A. Rassat, Angew. Chem. Int. Ed. Engl. 31 (1992) 180. (b) F. Kanno, K. Inoue, N. Koga, H. Iwamura, J. Am. Chem. Soc. 115 (1993) 847. (c) S. Fang, M.-S. Lee, D.A. Hrovat, W.T. Borden, J. Am. Chem. Soc. 117 (1995) 6727. Ullman, 1972, J. Am. Chem. Soc., 94, 7049, 10.1021/ja00775a031 The splittings may be attributed to the hyperfine coupling of four nuclei of 14N (nuclear spin number I=1) in the molecule 2a. The spectral simulation with a spin Hamiltonian containing the hyperfine coupling term as well as the fine structure term is under way. Bleany, 1952, Proc. R. Soc. Lon. Sect. A, 214, 451, 10.1098/rspa.1952.0181 An example of the effects of additional or excess electronic charge on the electronic spin state of homo-atomic carbon-based π-conjugated high-spin systems has been reported; (a) M. Matsushita, T. Momose, T. Shida, Y. Teki, T. Takui, K. Itoh, J. Am. Chem. Soc. 112 (1990) 4700. (b) M. Matsushita, T. Nakamura, T. Momose, T. Shida, Y. Teki, T. Takui, T. Kinoshita, K. Itoh, J. Am. Chem. Soc. 114 (1992) 7470. (c) M. Matsushita, T. Nakamura, T. Momose, T. Shida, Y. Teki, T. Takui, T. Kinoshita, K. Itoh, Bull. Chem. Soc. Jpn. 66 (1993) 1333. (d) K. Yamaguchi, Y. Toyoda, T. Fueno, Synth. Met. 19 (1987) 81. D. Shiomi, K. Sato, T. Takui, J. Phys. Chem. Sect. B (2001) in press. The organic salts can be prepared by combining the anionic biradicals with cationic monoradical derivatives of nitronyl nitroxide. When the potassium salts 1a and 2a were mixed with an iodide salt of p-N-methyl pyridinium nitronyl nitroxide with S=1/2 [12] in CHCl3 solutions, potassium iodide precipitated to give purely organic salts of pyridinium phenoxide. Magnetic properties of the organic salts will be reported elsewhere.