Syntheses, Structures, and Magnetic Properties of the Face-Centered Cubic Clusters [Tp<sub>8</sub>(H<sub>2</sub>O)<sub>12</sub>M<sub>6</sub>Fe<sub>8</sub>(CN)<sub>24</sub>]<sup>4+</sup> (M = Co, Ni)
收藏资源简介：
Reactions between K[TpFe(CN)3] (Tp- = hydrotris(1-pyrazolyl)borate) and M(ClO4)2·6H2O (M = Co or Ni) in a mixture of acetonitrile and methanol afford, upon crystallization via THF vapor diffusion, [Tp8(H2O)12Co6Fe8(CN)24](ClO4)4·12THF·7H2O (1) and [Tp8(H2O)12Ni6Fe8(CN)24](ClO4)4·12THF·7H2O (2). Both compounds contain cyano-bridged clusters with a face-centered cubic geometry, wherein octahedral CoII or NiII centers are situated at the face-centering sites. The results of variable-temperature magnetic susceptibility measurements indicate the presence of ferromagnetic exchange coupling within both molecules to give ground states of S = 7 and 10, respectively. Low-temperature magnetization data reveal significant zero-field splitting, with the best fits for the Co6Fe8 and Ni6Fe8 clusters yielding D = −0.54 and 0.21 cm-1, respectively; ac magnetic susceptibility measurements performed on both samples showed no evidence of the slow relaxation effects associated with single-molecule magnet behavior.
