Structural and spectroscopic studies of [bis(picrato)(pentaethylene glycol)lanthanide(III)] picrate complexes with Ln(III) = Sm, Dy and Ho

The Sm(III), Dy(III) and Ho(III) complexes with mixed pentaethylene glycol (EO5) and picrate (Pic^-) ligands were obtained and characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopic techniques. They are isostructural with general formula of [Ln(Pic)₂(EO5)]⁺(Pic)^- (Ln = Sm(III), Dy(III) and Ho(III)). X-ray investigations showed that all the three complexes consist of hexadentate EO5 ligand and two picrate anions, one chelated in bidentate manner and the other one is monodentate located on the opposite sides of the primary Ln1-EO5 coordination sphere in a nine coordination environment. The geometry of the Ln1-EO5 sphere is tricapped trigonal prismatic with both benzene rings almost vertical to each other. TGA spectra of the complexes showed a gradual decomposition started from 250 °C followed by a sharp decrease in weight loss at 265 °C.