The Structure of Mo7O246− Ion in the Crystal of Ammonium Heptamolybdate Tetrahydrate

Abstract

Abstract The structure of a discrete polyanion, Mo7O246−, in the crystal of ammonium heptamolybdate tetrahydrate, previously determined by Lindqvist, has been redetermined and refined by a two-dimensional, single crystal X-ray diffraction study. The positional parameters of the oxygen atoms, which were left undetermined in the previous investigation, have been determined. Lindqvist’s description of the structure still applies. However, the distortion of the polyanion has been found to be more pronounced than was previously assumed. Comparisons with molybdenum oxides and oxyacids are discussed with regard to the structure, the Mo–Mo distances and Mo–O distances.