title: Pentanuclear cyanide-bridged complexes based on highly anisotropic Co(II) seven-coordinate building blocks: synthesis, structure, and magnetic behavior.
abstract: Pentagonal-bipyramidal complexes [Co(DABPH)X(H(2)O)]X [X = NO(3) (1), Br (2), I (3)] were synthesized, and their magnetic behavior was investigated. Simulation of the magnetization versus temperature data revealed the complexes to be highly anisotropic (D ≈ +30 cm(-1)) and the magnitude of the anisotropy to be independent of the nature of the axial ligands. The reaction of 1 with K(3)[M(CN)(6)] (M = Cr, Fe) produces the pentametallic clusters [{Co(DABPH)}(3){M(CN)(6)}(2)(H(2)O)(2)] [M = Cr (4), Fe (5)]. Both clusters consist of three {Co(DABPH)} moieties separated by two {M(CN)(6)} fragments. In 4, the central and terminal Co(II) ions are bound to cyanide groups cis to one another on the bridging {Cr(CN)(6)}, whereas in 5, the connections are via trans cyanide ligands, resulting in the zigzag and linear structures observed, respectively. Magnetic investigation revealed ferromagnetic intramolecular interactions; however, the ground states were poorly isolated because of the large positive local anisotropies of the Co(II) ions. The effects of the local anisotropies appeared to dominate the behavior in 5, where the magnetic axes of the Co(II) ions were approximately colinear, compared to 4, where they were closer to orthogonal.
authors: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Sud 11, 91405 Orsay, France. luke.batchelor@u-psud.fr
authors: Luke J
authors: LJ
authors: Batchelor
authors: Marco
authors: M
authors: Sangalli
authors: Régis
authors: R
authors: Guillot
authors: Nathalie
authors: N
authors: Guihéry
authors: Remi
authors: R
authors: Maurice
authors: Floriana
authors: F
authors: Tuna
authors: Talal
authors: T
authors: Mallah