Synthesis and Magnetic Properties of Metal Complexes with Chelating Nitronylnitroxide and Iminonitroxide

Yoshioka, Naoki; Irisawa, Munetoshi; Abe, Masahiro; Aoki, Takashi; Aizawa, Naoyuki; Inoue, Hidenari; Ohba, Shigeru

doi:10.1080/10587259708044593

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…The highly planar five-membered chelate ring plays a very important role in the ferromagnetic interactions. On the other hand, in the case of the corresponding 2PyNN derivative, the intramolecular coupling in [Cu(ClO 4 ) 2 (2PyNN)] was antiferromagnetic . The reason arises from a severe nonplanar distortion to lose the orthogonality (Figure b) like the TEMPO and PROXYL cases .…”

Section: Discussionmentioning

confidence: 97%

“…On the other hand, in the case of the corresponding 2PyNN derivative, the intramolecular coupling in [Cu(ClO 4 ) 2 (2PyNN)] was antiferromagnetic. 23 The reason arises from a severe nonplanar distortion 24 to lose the orthogonality (Figure 8b) like the TEMPO and PROXYL cases. 19 Therefore, in contrast to the literature results, 3 having six-membered chelate rings showed exceptionally intramolecular ferromagnetic interaction.…”

Section: Discussionmentioning

confidence: 99%

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Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

2003

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A new chelating radical ligand 4ImNNH (2-(4-imidazolyl)-4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide) was prepared, and complexation with divalent transition metal salts gave complexes, [M(4ImNNH)(2)X(2)], which showed intermolecular ferromagnetic interaction in high probability (7 out of 10 paramagnetic compounds investigated here). The nitrate complexes (X = NO(3); M = Mn (1), Co (2), Ni (3), Cu (4)) crystallize isomorphously in monoclinic space group P2(1)/a. The equatorial positions are occupied with two 4ImNNH chelates and the nitrate oxygen atoms are located at the axial positions. Magnetic measurements revealed that the intramolecular exchange couplings in 1, 2, and 4 were antiferromagnetic, while that in 3 was ferromagnetic with 2J/k(B) = +85 K, where the spin Hamiltonian is defined as H = -2J(S(1).S(2) + S(2).S(3)) based on the molecular structures determined as the linear radical-metal-radical triads. The intramolecular ferromagnetic interaction in 3 is interpreted in terms of orthogonality between the radical pi and metal dsigma orbitals. Compounds 1-3 exhibited intermolecular ferromagnetic interaction ascribable to a two-dimensional hydrogen bond network parallel to the crystallographic ab plane. Complex 3 became an antiferromagnet below 3.4 K and exhibited a metamagnetic transition on applying a magnetic field of 5.5 kOe at 1.8 K. The complexes prepared from metal halides, [M(4ImNNH)(2)X(2)] (X = Cl, Br; M = Mn, Co, Ni, Cu), showed intramolecular antiferromagnetic interactions, which are successfully analyzed based on the radical-metal-radical system. The crystal structures determined here on 1-4, [Mn(4ImNNH)(2)Cl(2)], and [Cu(4ImNNH)(2)Br(2)] always have intermolecular hydrogen bonds of H(imidazole).X(axial ligand)-M, where X = NO(3), Cl, Br. This interaction seems to play an important role in molecular packing and presumably also in magnetic coupling.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

2003

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Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Luneau

Rey

2005

Coordination Chemistry Reviews

220

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Metamagnetic behavior of [Ni(4ImNNH)2(NO3)2] having a ground high-spin state (4ImNNH=4-imidazolyl nitronyl nitroxide)

Aoki

Ishida

Nogami

2003

Inorganic Chemistry Communications

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Synthesis and Magnetic Properties of Metal Complexes with Chelating Nitronylnitroxide and Iminonitroxide

Cited by 3 publications

References 8 publications

Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Metamagnetic behavior of [Ni(4ImNNH)2(NO3)2] having a ground high-spin state (4ImNNH=4-imidazolyl nitronyl nitroxide)

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Synthesis and Magnetic Properties of Metal Complexes with Chelating Nitronylnitroxide and Iminonitroxide

Cited by 3 publications

References 8 publications

Molecular Metamagnet [Ni(4ImNNH)2(NO3)2] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

Molecular Metamagnet [Ni(4ImNNH)2(NO3)2] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Metamagnetic behavior of [Ni(4ImNNH)2(NO3)2] having a ground high-spin state (4ImNNH=4-imidazolyl nitronyl nitroxide)

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Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions

Molecular Metamagnet [Ni(4ImNNH)₂(NO₃)₂] (4ImNNH = 4-Imidazolyl Nitronyl Nitroxide) and the Related Compounds Showing Supramolecular H-Bonding Interactions