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.

Abstract

The design, synthesis, and structural and magnetic properties of the two new bimetallic complexes [Sm(DMF)(4)(H(2)O)(2)Cr(CN)(6)].H(2)O and [Sm(DMF)(2)(H(2)O)(3)Cr(CN)(6)].H(2)O (DMF = N,N-dimethylformamide) are presented. [Sm(DMF)(4)(H(2)O)(2)Cr(CN)(6)].H(2)O was prepared by the reaction between Sm(3+) and [Cr(CN)(6)](3-) in a methanol-DMF solution, while [Sm(DMF)(2)(H(2)O)(3)Cr(CN)(6)].H(2)O was prepared by the reaction between Sm(3+), DMF, and [Cr(CN)(6)](3-) in the molar ratio of 1:2:1 in H(2)O. [Sm(DMF)(4)(H(2)O)(2)Cr(CN)(6)].H(2)O crystallizes in the monoclinic space group of P2(1)/c with a = 13.161(3) A, b = 12.928(3) A, c = 19.174(4) A, beta = 109.82(3) degrees, and Z = 4, while [Sm(DMF)(2)(H(2)O)(3)Cr(CN)(6)].H(2)O is in the triclinic space group P1 with a = 7.7535(1) A, b = 9.4307(3) A, c = 16.2905(5) A, alpha = 94.1590(14) degrees, beta = 100.0597(18) degrees, gamma = 100.9154(18) degrees, and Z = 2. The structure of [Sm(DMF)(4)(H(2)O)(2)Cr(CN)(6)].H(2)O possesses a cyano-bridged one-dimensional (1D) zigzag chain structure with alternating Sm(DMF)(4)(H(2)O)(2) and Cr(CN)(6) moieties. [Sm(DMF)(2)(H(2)O)(3)Cr(CN)(6)].H(2)O 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)(H(2)O)(3)](3+) units. Each [Sm(DMF)(2)(H(2)O)(3)](3+) unit, in turn, links three [Cr(CN)(6)](3-), generating a flat brick wall-like structure. Magnetic studies on [Sm(DMF)(2)(H(2)O)(3)Cr(CN)(6)].H(2)O 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)(H(2)O)(2)Cr(CN)(6)].H(2)O.