catena-Poly[tetra­sodium [[cis-dioxido-trans-bis­(sulfato-κO)molybdate(VI)]-μ-sulfato-κ2 O:O′]]

Single crystals of the title compound, {Na4[MoVIO2(SO4)3]}n, were grown from a melt of MoO3 and Na2SO4 in Na2S2O7. In contrast to the structure of the isoformular K compound, K4[MoVIO2(SO4)3], with its monomeric anion, this sodium analogue contains a polymeric anion of the type {[MoVIO2(SO4)2-μ-(SO4)]4−}n. The MoVI cations, surrounded by two tightly bonded O atoms and four O atoms of one bridging and two terminal sulfato ligands, form zigzag chains parallel to [100]. All four Na+ cations are situated between the anionic chains and have distorted octa­hedral coordination spheres

Tetra­potassium cis-dioxido-trans-bis­(sulfato-κO)sulfato(κ2 O,O′)molybdate(VI)

The title compound, K4[MoVIO2(SO4)3], was precipitated from a melt of molybdenum(VI) oxide and potassium sulfate in potassium disulfate. The compound contains monomeric [MoVIO2(SO4)3]4− anions, with the MoVI atom, both oxide ligands, and the S atom and both ligating O atoms of the bidentate sulfate group lying on a crystallographic mirror plane. One of the potassium cations is nine-coordinate, while the other is eight-coordinate