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)

Reactions between K[TpFe(CN)<sub>3</sub>] (Tp<sup>-</sup> = hydrotris(1-pyrazolyl)borate) and M(ClO<sub>4</sub>)<sub>2</sub>·6H<sub>2</sub>O (M = Co or Ni) in a mixture of acetonitrile and methanol afford, upon crystallization via THF vapor diffusion, [Tp<sub>8</sub>(H<sub>2</sub>O)<sub>12</sub>Co<sub>6</sub>Fe<sub>8</sub>(CN)<sub>24</sub>](ClO<sub>4</sub>)<sub>4</sub>·12THF·7H<sub>2</sub>O (<b>1</b>) and [Tp<sub>8</sub>(H<sub>2</sub>O)<sub>12</sub>Ni<sub>6</sub>Fe<sub>8</sub>(CN)<sub>24</sub>](ClO<sub>4</sub>)<sub>4</sub>·12THF·7H<sub>2</sub>O (<b>2</b>). Both compounds contain cyano-bridged clusters with a face-centered cubic geometry, wherein octahedral Co<sup>II</sup> or Ni<sup>II</sup> 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 <i>S</i> = 7 and 10, respectively. Low-temperature magnetization data reveal significant zero-field splitting, with the best fits for the Co<sub>6</sub>Fe<sub>8</sub> and Ni<sub>6</sub>Fe<sub>8</sub> clusters yielding <i>D</i> = −0.54 and 0.21 cm<sup>-1</sup>, respectively; ac magnetic susceptibility measurements performed on both samples showed no evidence of the slow relaxation effects associated with single-molecule magnet behavior.