Crystal structure of ammonium divanadium(IV,V) tellurium(IV) hepta-oxide.

The polyhedral building blocks of the layered inorganic network in the mixed-valence title compound, (NH4)(V(IV)O2)(V(V)O2)(TeO3), are vertex-sharing V(V)O4 tetra-hedra, distorted V(IV)O6 octa-hedra and TeO3 pyramids, which are linked by V-O-V and V-O-Te bonds, forming double layers lying parallel to (100). The presumed Te(IV) lone-pairs of electrons appear to be directed inwards into cavities in the double layers. The charge-balancing ammonium cations lie between the layers and probably inter-act with them via N-H⋯O hydrogen bonds.