Redetermination of ammonium metavanadate

The crystal structure of ammonium metavanadate, NH 4 VO 3 , a compound widely used as a starting material for the synthesis of vanadium and polyoxidovanadate compounds, had been determined twice using single-crystal X-ray data [Syneček & Hanic (1954). Czech. J. Phys . 4 , 120–129 (Weissenberg data); Hawthorne & Calvo (1977). J. Solid State Chem . 22 , 157–170 (four-circle diffractometer data)]. Its structure is now redetermined at higher resolution using Ag K α radiation, and the result is compared with the former refinements. Structural data for the polymeric [VO 3 ] ∞ chain remain unchanged, while more accurate parameters are obtained for the ammonium cation, improving the description of hydrogen-bonding interactions in the crystal structure.