Bimetallic Assemblies [Ni(L)₂]₃[Fe(CN)₆]X₂ (L = Ethylenediamine, Trimethylenediamine; X = PF₆^-, ClO₄^-) with a Three-Dimensional Network Extended through Fe^II−CN−Ni^II Linkages

Three-dimensional cyanide-bridged bimetallic assemblies [Ni(L)₂]₃[Fe^II(CN)₆]X₂ ((L, X) = (ethylenediamine (en), PF₆^-) (1), (trimethylenediamine (tn), PF₆^-) (2), (tn, ClO₄^-) (3)) were synthesized and structurally characterized. Compounds 1−3 crystallize in the trigonal system of the space group R3̄ with a = b = 13.743(1) Å, c = 17.802(2) Å, and Z = 3 for 1, a = b = 14.588(1) Å, c = 17.050(2) Å, and Z = 3 for 2, and a = b = 14.337(2) Å, c = 17.294(4) Å, and Z = 3 for 3. All the assemblies have an isotropic three-dimensional network structure extended through Fe−CN−Ni linkages. The network is based on a cube formed by 8 [Fe(CN)₆]^4- anions at the corners and 12 [Ni(L)₂]²⁺ cations at the edges. Two hexafluorophosphate or perchlorate anions are located in the cavity of the Fe₈Ni₁₂ cube and align along a diagonal axis that coincides with the c axis. Magnetic measurements show a ferromagnetic interaction between the nearest Ni^II ions through the diamagnetic Fe^II ion.