First transuranium mixed-ligand polyoxometalate complex

First mixed-ligand polyoxometalate complex of neptunium, K10.5H0.5[Np(BW11O39)(W5O18)]·15H2O, has been synthesized. Its structure has been determined using X-ray diffractometry and confirmed by electron and IR absorption spectroscopy. The structure consists of [Np(BW11O39)(W5O18)]11− anions, potassium cations and water molecules. The overall symmetry of the [Np(BW11O39)(W5O18)]11− anion can be approximated as Cs. Two tetradentate ligands, [W5O18]6− and [BW11O39]9−, are connected to an Np atom through lacunary O atoms, so that a square antiprismatic surrounding of Np is formed.