Expanding the crystal chemistry of uranyl peroxides: Synthesis and structures of Di- and triperoxodioxouranium(VI) complexes

Four compounds containing tri- and diperoxodioxouranium(VI) complexes have been synthesized under ambient conditions and structurally characterized. The crystal structures of Na-4(UO2)(O-2)(3)(H2O)(12) (monoclinic, P2(1)/c, a = 6.7883(6) angstrom, b = 16.001(2) angstrom, c = 16.562(2) angstrom, beta = 91.917(2)degrees, V = 1797.9(3) A(3), Z = 4) and Ca-2(UO2)(O-2)(3)(H2O)(9) (orthorhombic, Pbcn, a = 9.576(3) angstrom, b = 12.172(3) angstrom, c = 12.314(2) angstrom, V = 1435.4(6) A(3), Z = 4) contain clusters of triperoxodioxouranium(VI). These clusters are bonded through a network of H bonding to H2O groups and in the Ca compound by bonds to Ca2+ cations. In the crystal structure of Na2Rb4(UO2)(2)(O-2)(5)(H2O)(14) (orthorhombic, Pbcm, a = 6.808(2) angstrom, b = 16.888(6) angstrom, c = 23.286(8) angstrom, V = 2677.5(16) A(3), Z = 4), triperoxodioxouranium(VI) polyhedra share a peroxide edge, forming dimers of polyhedra of composition (UO2)(2)(O-2)(5)(6-). Adjacent dimers are linked through bonding to Rb+ cations and by H bonds to H2O groups. The crystal structure of K-6[(UO2)(O-2)(2)(OH)](2)(H2O)(7) (orthorhombic, Pcca, a = 15.078(8) angstrom, b = 6.669(4) angstrom, c = 23.526(13) angstrom, V = 2366(2) A(3), Z = 4) contains diperoxodioxouranium(VI) polyhedra that include two OH groups. These polyhedra share an OH-OH edge, forming dimers of composition (UO2)(2)(O-2)(4)(OH)(2)(6-). The dimers are linked by bonds to K+ cations and by H bonding to H2O groups.