Inorganic Chemistry, Vol.54, No.17, 8449-8455, 2015
Insertion of Trivalent Lanthanides into Uranyl Vanadate Layers and Frameworks
Two new uranyl vanadates have been prepared from hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction. The structure of (H3O)UO2VO4 (UVO-1) consists of anionic layers containing UO22+ pentagonal bipyramids coordinated by edge-sharing VO5, square pyramids, with the charge balanced by interlaminar H3O+ cations. Vanadium in (UO2)(3)(VO4)(2)(H2O)(3) (UVO-2) exists as monomeric VO4 tetrahedra coordinating to UO22+ pentagonal bipyramids, forming a 3D uranyl(VI) vanadate framework. Similar reactions with the addition of Ln(NO3)(3) (Ln = Nd, Eu) afford the three heterobimetallic lanthanide uranyl vanadate frameworks Nd(UO2)(3)(VO4)(3)(H2O)(11) (NdUVO-1), Eu(UO2)(3)(VO4)(3)(H2O)(10) (EuUVO-1), and Eu-2(UO2)(12)(VO4)(10)(H2O)(24) (EuUVO-2). In NdUVO-1 and EuUVO-1, Ln(3+) cations are inserted into the interlayer space of UVO-1 substituting for H3O+ and further bridging adjacent layers into 3D frameworks. Similarly, EuUVO-2 adopts the same sheet topology as UVO-2, with Eu3+ ions replacing some of the interlayer uranyl ions in UVO-2. Our work has demonstrated that uranyl vanadate extended structures are excellent hosts for further incorporation of trivalent lanthanide/ actinide cations and has provided a new way to create new heterobimetallic 4f Sf and Sf Sf compounds.