Synthesis and structure of a polymeric ten-coordinate rare earth metal complex with nta ligand: {[Eu^III(C-nta)(T-nta)]·3H₂O}_n with a novel cage-like 3-D structure

Abstract

The polymeric ten-coordinate rare earth metal (RE) complex with nta, {[Eu^III(C-nta)(T-nta)] · 3H₂O} _n , has been synthesized in aqueous solution and characterized by FT-IR, elemental analyses, TG-DTA and single-crystal X-ray diffraction technique. The {[Eu^III(C-nta)(T-nta)] · 3H₂O} _n crystallizes in the cubic system with P2₁3 space group, a = b = c = 12.4153(3) Å, V = 1913.69(8) ų, Z = 4, M = 582.24 g mol⁻¹, D _c = 2.021 Mg m⁻³, μ = 3.360 mm⁻¹, F(000) = 1148, and its structure is refined to R ₁(F) = 0.0204 for 1277 observed reflections [I ≥ 2.0σ(I)]. The coordination polyhedron adopts distorted C_3v mono-top-capped & tri-lateral-capped trigonal prismatic conformation (MT&TL-TP); the three-dimensional geometry is a cage-like 3-D structure. According to thermal analyses, the collapsing temperature of the crystal structure is 173°C, indicating that its crystal structure is very stable.

Keywords:

• Eu(III) ion
• Nitrilotriacetic acid (H₃nta)
• Coordination polymer
• Cage-like 3-D structure

Acknowledgments

We thank Professor K. Miyoshi and T. Mizuta, Faculty of Science, Hiroshima University, Japan, for instruction and Dr N. H. Hu, Changchun Institute of Applied Chemistry, Chinese Academy of Science, for the single crystal X-ray structural determination. We also thank the software Mercury 1.4 (free), which helps us to analyze the crystal and molecular structures. These projects were supported by the National Natural Science Foundation of China (No. 20371023).