Structure and Thermal Decomposition of Nd(III), Gd(III) and Tb(III) 2-Thiobarbiturates

Golovnev, N. N.; Molokeev, M. S.; Sterkhova, I., V Source: RUSSIAN JOURNAL OF INORGANIC CHEMISTRY, 64 (9):1146-1151; 10.1134/S0036023619090134 SEP 2019

Complexes [Ln2(H2O)62-Htba−O,O')4(Htba−O)2]n (Ln = Tb (I), Gd (II), Nd (III); and H2tba is thiobarbituric acid) have been synthesized. According to single-crystal X-ray diffraction, monoclinic crystals of I–III are isostructural. They contain three independent Htba ions (one terminal and two bridging) and two independent Ln3+ ions. Six Htba ligands (two terminal and four O,O'-bridging) and two water molecules are coordinated to one Ln3+ ion, and four O,O'-bridging Htba ions and four water molecules are coordinated to the other Ln3+ ion to form square antiprisms. The antiprisms are bound by Htba bridging ions into layers. Numerous hydrogen bonds and π–π interactions stabilize the structures of the compounds. Thermal decomposition of complexes I and II performed in air results in mixtures of oxides and oxysulfates, whereas complex III forms Nd2O2SO4.