The crystal structure of magnesium dimolybdate

The structure of magnesium dimolybdate, MgMo207, monoclinic with space group P2/c and a = 8.111 (2), b = 5.700 (1), c = 15.002 (3) ,~, fl = 115.26 (2) °, Z = 4, was determined by the heavy-atom method and refined by full-matrix least squares to an R of 0.095 for 2558 counter reflexions. The Mo202pyro-anion consists of two corner-sharing MoO 4 tetrahedra, which are twisted from the ideal eclipsed configuration by an average of 12.3 °. Mo207 groups form anionic sheets parallel to the (100) plane. Mg 2÷ ions are situated between the anionic sheets in a distorted-octahedral environment of O atoms. MgO 6 octahedra share one edge forming Mg2Oi0 units.