SYNTHESIS AND CHARACTERIZATION OF LANTHANIDE PICRATE COMPLEXES WITH TRIPIPERIDINOPHOSPHINE OXIDE

Compounds with the general formula Ln(pic)(3) . 2tpppo (Ln: La-Lu, Y; pic=picrate; tpppo=tripipendinophosphine oxide) were synthesized by re action of the hydrated picrates with tpppo in absolute ethanol. IR abs orption spectra were interpreted in terms of the coordination of tpppo through the oxygen and picrate anions that are bidentate, coordinated to the central ions through the phenoxo group and one oxygen of an or tho-nitro group. Conductance measurements in acetonitrile solutions sh ow that the complexes behave as non-electrolytes. X-ray powder pattern s show only one isomorphous series. Phosphorus-31 NMR showed a signal shift to lower field with relation to the free ligand, showing evidenc e of bonding through the phosphoryl group. The parameters obtained fro m the absorption spectrum of the Nd compound indicate that the metal-l igand bonds present some covalent character. The emission spectra of t he europium and samarium adducts were determined. The spectrum of the europium compound was interpreted in terms of D-2d distorted towards C -2v symmetry for the Eu(O)(8) chromophore.