K(MoO₂)₄O₃(AsO₄)

A new compound with a non-centrosymmetric structure, potassium tetra­kis­[dioxomolybdenum(IV)] arsenate trioxide, K(MoO₂)₄O₃(AsO₄), has been synthesized by a solid-state reaction. The [(MoO₂)₄O₃(AsO₄)]⁺ three-dimensional framework consists of single arsenate AsO₄ tetra­hedra, MoO₆ octa­hedra, MoO₅ bipyramids and bi­octa­hedral units of edge-sharing Mo₂O₁₀ octa­hedra. The [Mo₂O₈]_∞ octa­hedral chains running along the a-axis direction are connected through their corners to the AsO₄ tetra­hedra, MoO₆ octa­hedra and MoO₅ bipyramids, so as to form large tunnels propagating along the a axis in which the K⁺ cations are located. This structure is compared with compounds containing M₂O₁₀ (M = Mo, V, Fe) dimers and with those containing M₂O₈ (M = V) chains.