ChemEngineering (Jan 2021)

Successive Crystallization of Organically Templated Uranyl Sulfates: Synthesis and Crystal Structures of [pyH](H<sub>3</sub>O)[(UO<sub>2</sub>)<sub>3</sub>(SO<sub>4</sub>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>], [pyH]<sub>2</sub>[(UO<sub>2</sub>)<sub>6</sub>(SO<sub>4</sub>)<sub>7</sub>(H<sub>2</sub>O)], and [pyH]<sub>2</sub>[(UO<sub>2</sub>)<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>]

  • Evgeny V. Nazarchuk,
  • Dmitri O. Charkin,
  • Oleg I. Siidra

DOI
https://doi.org/10.3390/chemengineering5010005
Journal volume & issue
Vol. 5, no. 1
p. 5

Abstract

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Three new uranyl sulfates, [pyH](H3O)[(UO2)3(SO4)4(H2O)2] (1), [pyH]2[(UO2)6(SO4)7(H2O)] (2), and [pyH]2[(UO2)2(SO4)3] (3), were produced upon hydrothermal treatment and successive isothermal evaporation. 1 is monoclinic, P21/c, a = 14.3640(13), b = 10.0910(9), c = 18.8690(17) Å, β = 107.795(2), V = 2604.2(4) Å3, R1 = 0.038; 2 is orthorhombic, C2221, a = 10.1992(8), b = 18.5215(14), c = 22.7187(17) Å, V = 4291.7(6) Å3, R1 = 0.030; 3 is orthorhombic, Pccn, a = 9.7998(8), b = 10.0768(8), c = 20.947(2) Å, V = 2068.5(3) Å3, R1 = 0.055. In the structures of 1 and 2, the uranium polyhedra and SO4 tetrahedra share vertices to form ∞3[(UO2)3(SO4)4(H2O)2]2− and ∞3[(UO2)6(SO4)7(H2O)]2− frameworks featuring channels (12.2 × 6.7 Å in 1 and 12.9 × 6.5 Å in 2), which are occupied by pyridinium cations. The structure of 3 is comprised of ∞2[(UO2)2(SO4)3]2− layers linked by hydrogen bonds donated by pyridinium cations. The compounds 1–3 are formed during recrystallization processes, in which the evaporation of mother liquor leads to a stepwise loss of hydration water.

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