Collect. Czech. Chem. Commun. 1989, 54, 645-652

The structure of the compounds Na24As2Z22O83 and its relationship to the structure of Na2Z2O7 (Z = Mo, W)

Milan Drátovskýa, Ctirad Novákb, Václav Petříčekb and Václav Štengla

a Department of Inorganic Chemistry, Charles University, 128 40 Prague 2
b Institute of Physics, Czechoslovak Academy of Sciences, 180 40 Prague 8


X-ray study of the structure of the compounds Na24As2Z22O83 (Z = Mo, W) indicated that these compounds and the compounds Na2Z2O7 are all isomorphic. They crystallize in the orthorhombic system with a space group of Cmca. The compound Na24As2Z22O83 is formed by replacing part of the Mo atoms by As in the centres of the oxygen tetrahedra in the structure of Na2Mo2O7. This substitution As ##c Mo results in loss of one oxygen atom for every two arsenic atoms in the Na2Mo2O7 structure so that two AsO4 tetrahedra are joined through an oxygen apex to form a As-O-As bond. The exact atomic ratio As:Mo = 1:11 in the studied compounds was also sufficiently confirmed by study of the phase diagrams NaAsO3-Na2Z2O7.