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Synthesis, Crystal Structure, and Magnetic Properties of Two Cyano-Bridged Bimetallic 4f−3d Arrays with One-Dimensional Chain and Two-Dimensional Brick Wall Molecular Structures

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posted on 09.10.2001 by Hui-Zhong Kou, Song Gao, Xianglin Jin
The design, synthesis, and structural and magnetic properties of the two new bimetallic complexes [Sm(DMF)4(H2O)2Cr(CN)6]·H2O and [Sm(DMF)2(H2O)3Cr(CN)6]·H2O (DMF = N,N-dimethylformamide) are presented. [Sm(DMF)4(H2O)2Cr(CN)6]·H2O was prepared by the reaction between Sm3+ and [Cr(CN)6]3- in a methanol−DMF solution, while [Sm(DMF)2(H2O)3Cr(CN)6]·H2O was prepared by the reaction between Sm3+, DMF, and [Cr(CN)6]3- in the molar ratio of 1:2:1 in H2O. [Sm(DMF)4(H2O)2Cr(CN)6]·H2O crystallizes in the monoclinic space group of P2(1)/c with a = 13.161(3) Å, b = 12.928(3) Å, c = 19.174(4) Å, β = 109.82(3)°, and Z = 4, while [Sm(DMF)2(H2O)3Cr(CN)6]·H2O is in the triclinic space group P1̄ with a = 7.7535(1) Å, b = 9.4307(3) Å, c = 16.2905(5) Å, α = 94.1590(14)°, β = 100.0597(18)°, γ = 100.9154(18)°, and Z = 2. The structure of [Sm(DMF)4(H2O)2Cr(CN)6]·H2O possesses a cyano-bridged one-dimensional (1D) zigzag chain structure with alternating Sm(DMF)4(H2O)2 and Cr(CN)6 moieties. [Sm(DMF)2(H2O)3Cr(CN)6]·H2O consists of cyano-bridged neutral brick wall-like layers in which each [Cr(CN)6]3- unit uses three cyanide groups in the meridional arrangement to connect with three [Sm(DMF)2(H2O)3]3+ units. Each [Sm(DMF)2(H2O)3]3+ unit, in turn, links three [Cr(CN)6]3-, generating a flat brick wall-like structure. Magnetic studies on [Sm(DMF)2(H2O)3Cr(CN)6]·H2O showed a magnetic-phase transition temperature below 4.2 K and a coercive field of 100 Oe at 1.85 K, while no long-range magnetic ordering was observed in the 1D complex [Sm(DMF)4(H2O)2Cr(CN)6]·H2O.

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