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Crystal structure of the heptamolybdate(VI)(paramolybdate) ion, [Mo7O24]6–, in the ammonium and potassium tetrahydrate salts

Howard T. Evans·B. M. Gatehouse·P. Leverett
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Abstract

The crystal structures of the isomorphous salts M I 6 [Mo 7 O 24 ],4H 2 O (M = NH 4 or K) have been refined by three-dimensional X -ray diffraction methods. Unit cell dimensions of these monoclinic compounds, space group P 2 1 / C with Z = 4, are, ammonium salt: a = 8·3934 ± 0·0008, b = 36·1703 ± 0·0045, c = 10·4715 ± 0·0011 Å, β= 115·958°± 0·008°; and potassium salt: a = 8·15 ± 0·02, b = 35·68 ± 0·1, c = 10·30 ± 0·02 Å, β= 115·2°± 02°. By use of multiple Weissenberg patterns, 8197 intensity data (Mo- K α radiation) for the ammonium compound and 2178 (Cu- K α radiation) for the potassium compound were estimated visually and used to test and refine Lindqvist's proposed structure in the space group P 2 1 / c . Lindqvist's structure was confirmed and the full matrix least-squares isotropic refinement led to R 0·076 (ammonium) 0·120 (potassium), with direct unambiguous location of the cations and water molecules in the potassium compound.

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Howard T. Evans, B. M. Gatehouse, P. Leverett. 1975. Crystal structure of the heptamolybdate(VI)(paramolybdate) ion, [Mo7O24]6–, in the ammonium and potassium tetrahydrate salts. https://doi.org/10.1039/dt9750000505

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