Structure and magnetic properties of the two-dimensional ferrimagnet (NEt4)[{Mn(salen)}2Fe(CN)6]:: Investigation of magnetic anisotropy on a single crystal

The title compound, (NEt4)[{Mn(salen)}(2)Fe(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, salen(2-) = 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 P2(1)/c with cell dimensions of a = 12.3660(8) Angstrom, b = 15.311 (1) Angstrom, c = 12-918(1) Angstrom, beta = 110.971(4)degrees, Z= 2 and is isostructural to the previously synthesized compound, (NEt4)[{Mn(5-Clsalen)}(2)Fe(CN)(6)](5-Clsalen(2)- = 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 T-c = 7.7 K and exhibits hysteresis with a remnant magnetization of 13.44 cm(3).mol(-1) (M/Nmu(B) = 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(Ill) ions.