A triclinic polymorph of dicadmium divanadate(V)

The title compound, Cd₂V₂O₇, was obtained under hydro­thermal conditions. Different from the known monoclinic form, the new polymorph of Cd₂V₂O₇ has triclinic symmetry and is isotypic with Ca₂V₂O₇. The building units of the crystal structure are two Cd²⁺ cations, with coordination numbers of six and seven, and two V atoms with a tetra­hedral and a significantly distorted trigonal-pyramidal coordination environment, respectively. Two VO₅ pyramids share an edge and each pyramid is connected to one VO₄ tetra­hedron via a corner atom, forming an isolated V₄O₁₄^8- anion. These anions are arranged in sheets parallel to (-211) and are linked through the Cd²⁺ cations into a three-dimensional framework structure.