Octahedral Niobium Chloride Clusters as Building Blocks of Templated Prussian Blue Framework Analogues

The preparation, structure, and magnetic properties of the first three-dimensional framework containing octahedral niobium cyanochloride clusters as building units are reported. Reactions of aqueous solutions of (Me4N)2K2[Nb6Cl12(CN)6] (2) with aqueous solutions of MnCl2 result in the precipitation of the compound (Me4N)2[MnNb6Cl12(CN)6] (3). The structure of 3 was determined from single-crystal X-ray diffraction study (crystal data: cubic, Fm3m (No. 225), a = 15.513(4) (angstrom), V = 3733.2(12) (angstrom)3, Z = 4). Its 3D framework is based on edge-bridged [Nb6Cl12]2+ clusters and Mn2+ ions bridged by cyanide ligands to form a cfc lattice [MnNb6Cl12(CN)6]2- in which all tetrahedral sites are occupied by the cations (Me4N)+ which act as charge compensating template. The structure of 3 can be considered as an expansion of the Prussian blue framework in which [Fe(CN)6]4- is replaced by the cluster [Nb6Cl12(CN)6]4-. Magnetic susceptibility measurements indicate that Mn2+ is present in a high spin d5 configuration. No magnetic ordering is observed.