Hydrated lanthanides picrate complexes with cis-1,3-dithiane-1,3-dioxide (cis-DTSO2). Structure of the Ho compound

Abstract

Compounds with composition [Ln(cis-DTSO2)4(H2O)2] (pic)3 (pic=picrate, Ln=Pr-Lu and Y) were obtained by reaction of hydrated lanthanide picrate with cis-DTSO2 in absolute ethanol. The adducts were characterized by elemental analyses and IR spectra. The parameters obtained from the absorption spectrum of the solid Nd compound indicate that the metal-ligand bonds present weak covalent character. The low intensity emission spectrum obtained at 77 K for the Eu compound indicates the existence of dimeric species. X-ray powder patterns show only one isomorphous series. X-ray single-crystal data of the holmium compound showed that the crystal system is triclinic, space group P1̄, a=13.387(1) Å, b=14.243(1) Å, c=14.965(1) Å, α=99.879(8)°, β=102.063(9)°, γ=101.620(1). The Ho ion achieves a coordination number of eight by the bonding of two oxygens of one bidentate cis-DTSO2, four oxygens of four monodentate cis-DTSO2, one of which acts as a bridge between two neighboring Ho ions, and two water molecules, giving rise to a distorted square antiprism polyhedron. The picrate anions are not bonded to the Ho(III) ion. The crystal packing is governed by an intricate net of hydrogen bonds. © 2001 Elsevier Science B.V.