Hydrates of Lanthanide(III) 2-Thiobarbiturates: Synthesis, Structure, and Thermal Decomposition

The hydrates Ln(Htba)₃ ∙ 3H₂O (Ln = Yb (I), Er (II), Ho (III); Н₂tba = 2-thiobarbituric acid), Ln(Htba)₃ ∙ 2H₂O and Ln(Htba)₃ ∙ 8H₂O were crystallized from aqueous solutions. According to single-crystal X-ray diffraction analysis data, the structure of monoclinic crystals of isostructural complexes I–III was [Ln₂(H₂O)₆(μ₂-Htba-О,O')₄(Htba-О)₂]_n. The formation of isostructural Ln(Htba) ∙ 2H₂O (Ln = La, Ce, Eu, Yb, Lu), Ln(Htba)₃ ∙ 8H₂O (Ln = Eu, Tb, Ho, Yb) and Y(Htba)₃ ∙ nH₂O (n = 2, 8) was confirmed by the comparison of X-ray diffraction patterns, and their composition was determined by elemental and thermal analyses. The stability of crystal hydrates under heating in an air atmosphere and in contact with their saturated solutions was studied.