Mild Hydrothermal Synthesis of Zirconium-Containing Fluorides: K2[M(H2O)6][Zr2F12] (M = Fe, Co), Rb2[M(H2O)6][Zr2F12] (M = Fe, Co, Ni, Cu, Zn), Cs2[M(H2O)6][Zr2F12] (M = Fe, Co, Ni), and Cs2Zr3Mn3F20.

High-quality single crystals of the formula K2[M(H2O)6][Zr2F12] (M = Fe, Co), Rb2[M(H2O)6][Zr2F12] (M = Fe, Co, Ni, Cu, Zn), Cs2[M(H2O)6][Zr2F12] (M = Fe, Co, Ni), and Cs2Zr3Mn3F20 were obtained through a mild hydrothermal synthesis. The new materials crystallize in the monoclinic space group P21/n. The crystal structures and chemical compositions were determined using single crystal and powder X-ray diffraction. The thermal and optical properties of these materials are reported. UV-vis diffuse reflectance data identifies d-d electronic transitions of the Co-, Ni-, and Cu-containing compounds. Each hydrated compound (except the Fe containing compounds) exhibits similar thermal decomposition, fully dehydrating by 200 °C based on thermogravimetric analysis measurements. Magnetic measurements indicate that the new compositions are paramagnetic down to 2 K.