Structural studies on the actinide carboxylates (VII) The crystal and molecular structure of potassium maleate hydrogenmaleate dioxouranate (VI); [UO2(C4H2O4)K(C4H3O4)]

The title compound crystallizes in the triclinic system, space group $\text{P}\text{1}$ with a = 11.512(3), b = 9.387(3), c = 6.757(2) Å, α = 105.6(4), β = 96.8(4) and γ = 107.0(4)° and Z = 2. The structure is built up from two distinct coordination polyhedra, one is formed by the uranium which is at a centre of a pentagonal bipyramid, the other by the potassium cations heptacoordinate to oxygen atoms either belonging to the maleic ligands or to the uranyl group. The uranium polyhedra are connected through bridging maleato groups. The maleato-U-maleato chains in the direction of the c axis are held together through the potassium coordination polyhedra.