Synthesis, characterization and thermal decomposition of Sb^III-M-Sb^III type trinuclear complexes of ethylenediamine-N, N, N′, N′-tetraacetate (M:Co(II), La(III), Nd(III), Dy(III))

Abstract

Four ethylenediamine-N,N,N′,N′-tetraacetate complexes with Sb(III)-M-Sb(III) polynuclear structure (M=Co(II), La(III), Nd(III), Dy(III)) are synthesized. [Sb₂-μ₄-(EDTA)₂Co(H₂O)₂]·5.15H₂O is characterized by single crystal X-ray diffraction. The crystal structure of [Sb₂-μ₄-(EDTA)₂Co(H₂O)₂]·5.15H₂O belongs to monoclinic system, space group P2₁/n, lattice parameters: a=6.9969(2), _b=20.8705(4), _c=10.8106(2) Å, β=90.031(1)°, _V=1578.66(6) ų, _Z=2, _{M r}=1007.76, _{D c}=2.120 g cm⁻³, _F(000)=1001, μ=2.323 mm⁻¹, the final _R=0.0235 and _wR=0.0629 for 3480 observed reflections (_I>2σ(_I)). The powder X-ray diffraction patterns of the complexes are also measured. Elemental analyses, FTIR spectra, TG-DSC and DTA of [Sb₂(EDTA)₂Ln]NO₃·_nH₂O are performed. FTIR spectra reveal that the antimony and other metallic ions were connected through the carboxylate bridges. The thermal analysis can demonstrate the complex formation of the antimony, other metallic ions and EDTA. The possible pyrolysis reactions in the thermal decomposition process of the complexes, the experimental and calculated percentage mass losses are also given.