Crystal structure of polymer hexaaqua-hexakis(2-thiobarbiturato)dieuropium(III)

Complex Eu₂(HTBA)₆(H₂O)₆] _n (I), where H₂TBA is 2-thiobarbituric acid C₄H₄N₂O₂S, is synthesized. Its structure is determined by X-ray diffraction analysis (CIF file CCDC 987519). The crystals of complex I are monoclinic: a = 14.1033(4) Å, b = 10.0988(4) Å, c = 15.4061(5) Å, β = 110.003(1)°, V = 2061.9(1) ų, space group P2/n, Z = 2. All three independent ligands HTBA^? are coordinated to Eu³⁺ through oxygen atoms. Six HTBA^? ions (two terminal and four bridging) and two water molecules are coordinated to one of the independent Eu³⁺ ions. The second Eu³⁺ ion is bound to four bridging HTBA^? ions and four water molecules. The coordination polyhedra are square antiprisms. The bridging HTBA^? ions join the antiprisms into layers. The structure is stabilized by numerous hydrogen bonds and the π-π interaction between HTBA^?.