Synthesis, characterization and thermal behavior of some addition compounds between rare earth picrates (pic) and 2,2 '-dithiobis(pyridine-N-oxide)

Rare earth picrates addition compounds with 2,2'-dithiobis(pyridine-N-oxide ) (dithio) were synthesized and characterized. CHN analysis suggest a gener al formula Ln(pic)(3).1.5dithio.4H(2)O (Ln = La, Nd, Eu, Dy, Ho). IR spectr a indicate: (a) the presence of water molecules; (b) the presence of picrat e in bidentade form; and (c) a bond of dithio to the RE through NO groups. Parameters, calculated from Nd absorption spectra at room temperature are i n agreement with a small covalent character of the Ln:L interaction. Thermogravimetric data under N-2 and air atmospheres, show that: (a) the wa ter molecules loss is the first decomposition step (up to 453 K); (b) the r esidue, at ca. 1173 K, is essentially Ln(2)O(3). (C) 2000 Elsevier Science B.V. All rights reserved.