ic035464n_si_001.cif (94.45 kB)

Crystal Structures and Magnetic Properties of Two Low-Dimensional Materials Constructed from [MnIII(salen)H2O]+ and [M(CN)8]3-/4- (M = Mo or W) Precursors

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posted on 03.05.2004 by Paweł Przychodzeń, Krzysztof Lewiński, Maria Bałanda, Robert Pełka, Michał Rams, Tadeusz Wasiutyński, Carine Guyard-Duhayon, Barbara Sieklucka
The syntheses, X-ray structures, and magnetic behaviors of two new cyano-bridged assemblies, the molecular [MnIII(salen)H2O]3[WV(CN)8]·H2O (1) and one-dimensional [Mn(salen)(H2O)2]2{[Mn(salen)(H2O)][Mn(salen)]2[Mo(CN)8]}·0.5ClO4·0.5OH·4.5H2O (2), are presented. Compound 1 crystallizes in the monoclinic system, has space group P21/c, and has unit cell constants a = 13.7210(2) Å, b = 20.6840(4) Å, c = 20.6370(2) Å, and Z = 4. Compound 2 crystallizes in the triclinic system, has space group P1̄, and has unit cell dimensions a = 18.428(4) Å, b = 18.521(3) Å, c = 18.567(4) Å, and Z = 2. The structure of 1 consists of the asymmetric V-shaped Mn−NC−W−NC−Mn−Ophenolate−Mn molecules, where W(V) coordinates with [Mn(salen)H2O] and singly phenolate-bridged [Mn(salen)H2O]2 moieties through the neighboring cyano bridges. The [WV(CN)8]3- ion displays distorted square-antiprism geometry. The structure of 2 consists of the cyano-bridged {Mn3IIIMoIV}n- repeating units linked by double phenolate bridges into one-dimensional zigzag chains. The Mn(III) centers are bound to Mo(IV) of square-antiprism geometry through the neighboring cyano bridges. The magnetic studies of 1 reveal the antiferromagnetic intramolecular interactions through the CN and phenolate bridges and the relatively weak intermolecular interactions. Compound 1 becomes antiferromagnetically ordered below TN = 4.6 K. The presence of the magnetic anisotropy is documented with the M(H) measurements carried out for both polycrystalline and single-crystal samples. At T = 1.9 K, the spinflop transition is observed in the field of 18 kOe applied parallel to the bc plane, which is the easy plane of magnetization. Field dependence of magnetization of 1 shows field-induced metamagnetic behavior from the antiferromagnetic ground state of ST = 3/2 to the state of ST = 5/2. The magnetic properties of 2 indicate a weak antiferromagnetic interaction between Mn(III) centers in double-phenolate-bridged [MnIII(salen)]2 dinuclear subunits and a very weak ferromagnetic interaction between them through the diamagnetic [MoIV(CN)8]4- spacer.