Diguanidinium hexafluoridogermanate(IV) - an organic-inorganic hybrid salt with an antifluorite topology

Polycrystalline diguanidinium hexafluoridogermanate (IV) was obtained by co-precipitation from solutions of diguanidinium carbonate and germanium dioxide in 48 % hydrogen fluoride. The [C(NH2)(3)](2)[GeF6] structure was refined from single crystal X-ray diffractometer data: [C(NH2)(3)](2)[TiF6] type, C2/m, a = 1276.67(8), b = 732.70(5), c = 616.37(5) pm, b = 114.497(5)degrees, wR = 0.0700, 1033 F-2 values, 53 variables. The trigonal planar [C(NH2)(3)](+) cations and the octahedral [GeF6](2-) anions are condensed to double layers through strong H center dot center dot center dot F hydrogen bonds (208-213 pm H center dot center dot center dot F). The centers of gravity of the two building units have an antifluorite-like topology.