Crystal structure of a trigonal polymorph of aqua-dioxidobis(pentane-2,4-dionato-κ

[UO2(acac)2(H2O)] is constructed from one uran­yl(VI) unit, two monoanionic acetyl­acetonate (acac) ligands and one aqua ligand. The U atom exhibits a UO7 distorted penta­gonal–bipyramidal coordination geometry; four O atoms from two chelating bidentate acac ligands and one O atom of a aquo ligand (Ow) form the equatorial plane while two uran­yl(VI) O atoms are located at the axial positions.
The title compound, [UO2(acac)2(H2O)] consists of a uran­yl(VI) unit ([O=U=O]2+) coordinated to two monoanionic acetyl­acetonate (acac, C5H7O2) ligands and one water mol­ecule. The asymmetric unit includes a one-half of a uranium atom, one oxido ion, one-half of a water mol­ecule and one acac ligand. The coordination about the uranium atom is distorted penta­gonal–bipyramidal. The acac ligands and Ow atom comprise the equatorial plane, while the uranyl O atoms occupy the axial positions. Inter­molecular hydrogen bonding between complexes results in the formation of two-dimensional hexa­gonal void channels along the c-axis direction with a diameter of 6.7 Å. The monoclinic (P21/c space group) polymorph was reported by Alcock & Flanders [(1987). Acta Cryst. C43, 1480–1483].