Triclinic sodium tungsten oxide, Na5W14O44

The structure of the title compound, pentasodium tetradecatungsten tetratet racontaoxide, is built up of groups of four layers of WO6 octahedra similar to those found in the hexagonal tungsten bronzes, but displaced relative t o each other so that no tunnels of trigonal and hexagonal sections are form ed. These groups are linked together through a layer of a different type co nsisting of isolated WO5 trigonal bipyramids. The Na atoms are distributed in the hexagonal holes of the above layers, being coordinated in all cases by eight O atoms in a hexagonal bipyramidal arrangement.