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 Na4(UO2)(O2)3(H2O)12 (monoclinic, P21/c, a =
6.7883(6) Å, b = 16.001(2) Å, c = 16.562(2) Å, β = 91.917(2)°, V = 1797.9(3) Å3, Z = 4) and Ca2(UO2)(O2)3(H2O)9 (orthorhombic, Pbcn, a = 9.576(3) Å, b = 12.172(3) Å, c = 12.314(2) Å, V = 1435.4(6) Å3, 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(O2)5(H2O)14 (orthorhombic,
Pbcm, a = 6.808(2) Å, b = 16.888(6) Å, c = 23.286(8) Å, V = 2677.5(16) Å3, Z = 4), triperoxodioxouranium(VI)
polyhedra share a peroxide edge, forming dimers of polyhedra of composition (UO2)2(O2)56-. Adjacent dimers are
linked through bonding to Rb+ cations and by H bonds to H2O groups. The crystal structure of K6[(UO2)(O2)2(OH)]2(H2O)7 (orthorhombic, Pcca, a = 15.078(8) Å, b = 6.669(4) Å, c = 23.526(13) Å, V = 2366(2) Å3, Z = 4)
contains diperoxodioxouranium(VI) polyhedra that include two OH groups. These polyhedra share an OH−OH
edge, forming dimers of composition (UO2)2(O2)4(OH)26-. The dimers are linked by bonds to K+ cations and by H
bonding to H2O groups.