Layered polyhydrate 18-crown-6C3H7NH3F.10H2O

New polyhydrate 18-crown-6C₃H₇NH₃F-10H₂O which melts incongruently at —0.8̊C has been found in the 18-crown-6-C₃H₇NH₃F-H₂O system; a single crystal X-ray structure of this layered hydrate is reported, in which layers of water molecules and fluoride anions are made up of tetra-, penta- and heptagons and also contain vacant polyhedral cavities; the crown ether complexes with cations C₃H₇NH₃ ⁺ are situated between water-fluoride layers and do not form hydrogen bonds with the molecules of the layers.