Synthesis and characterization of lanthanide trifluoroacetate complexes with 3-picoline-N-oxide.

Abstract

Complexes with composition Ln(F3C-COO)3•2(3-picNO)•ξH2O were synthesized. According to X-ray powder patterns and IR data five series of isomorphous compounds were detected: LaNd; SmEu; Gd>Tm, Y; Ho, Er, Tb; Dy, Yb, Lu. They behave as nonelectrolytes in methanol. IR spectra show a shift of νNO to lower frequencies, as compared with the free ligand, as a result of coordination through the oxygen. The bands attributed to the anions indicate two modes of coordination. The neodymium spectrum at 77 K shows that the central ion is not involved in a cubic site. Electrostatic bonds between Nd3+ and ligands were evidenced by the nephelauxetic, Sinha's parameters and covalent factor from the room temperature spectrum. Using the electronic emission spectrum, at 77 K, it was possible to conclude that europium ions present two different symmetry sites, since a splitting of the 5D0 → 7F9 band was observed. The complex species are probably polymeric or at least dimeric, and europium ions are involved in two different sites, but with the same C3ν symmetry.