ic026261m_si_001.cif (18.55 kB)

Structure and Magnetic Properties of the Two-Dimensional Ferrimagnet (NEt4)[{Mn(salen)}2Fe(CN)6]:  Investigation of Magnetic Anisotropy on a Single Crystal

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posted on 25.04.2003 by Hitoshi Miyasaka, Hidenori Ieda, Naohide Matsumoto, Ken-ichi Sugiura, Masahiro Yamashita
The title compound, (NEt4)[{Mn(salen)}2Fe(CN)6] (1), was synthesized via a 1:1 reaction of [Mn(salen)(H2O)]ClO4 with (NEt4)3[Fe(CN)6] in a methanol/ethanol medium (NEt4+ = tetraethylammonium cation, salen2- = N,N-ethylenebis(salicylidene)iminate). The two-dimensional layered structure of 1 was revealed by X-ray crystallographic analysis:  1 crystallizes in monoclinic space group P21/c with cell dimensions of a = 12.3660(8) Å, b = 15.311(1) Å, c = 12.918(1) Å, β = 110.971(4)°, Z = 2 and is isostructural to the previously synthesized compound, (NEt4)[{Mn(5-Clsalen)}2Fe(CN)6] (5-Clsalen2- = N,N-ethylenebis(5-chlorosalicylidene)iminate; Miyasaka, H.; Matsumoto, N.; Re, N.; Gallo, E.; Floriani, C. Inorg. Chem. 1997, 36, 670). The Mn ion is surrounded by an equatorial salen quadridentate ligand and two axial nitrogen atoms from the [Fe(CN)6]3- unit, the four Fe−CN groups of which coordinate to the Mn ions of [Mn(salen)]+ units, forming a two-dimensional network having [−Mn−NC−Fe−CN−]4 cyclic repeating units. The network is spread over the bc-plane of the unit cell, and the layers are stacked along the a-axis. The countercation NEt4+ is located between the layers. Compound 1 is a ferrimagnet with Tc = 7.7 K and exhibits hysteresis with a remnant magnetization of 13.44 cm3·mol-1 (M/NμB = 2.4) at zero field and a coercivity of 1000 Oe when the powder sample was measured at 1.9 K. Magnetic measurements of a direction-arranged single crystal were also carried out. The orientation of the crystallographic axes of a selected single crystal was determined by X-ray analysis, and magnetization was measured when an external field was applied in the a*, b, and c directions. The magnetization in the a* direction increased more easily than those in the b and c directions below the critical temperature. No hysteresis was observed only for the measurement in the a* direction, indicating the presence of strong structural anisotropy with potential anisotropy on Mn(III) ions.