Mg(4)Sb(2)O(9) of the ilmenite structure type.

Single crystals of the title compound, tetra-magnesium dianti-monate(V), were obtained by the slow cooling method with K(2)CO(3). The structure is isotypic with ilmenite, which is constructed by the alternate stacking of layers consisting of metal-oxygen coordination octa-hedra. In each layer, the octa-hedra are connected by sharing edges so as to make holes. One of the two non-equivalent metal sites is fully occupied by Mg (3 symmetry), while the second metal site (3 symmetry) is disordered and occupied by Mg and Sb with occupation factors of 1/3 and 2/3, respectively.