Mass spectral studies of lanthanide chelates. II. Lanthanide chelates of three fluorinated β-diketones

Abstract

The lanthanide chelates MetL₃,nH₂O (Met = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, or Yb; L = PhCO= CHCOCF₃, p-MeC₆H₄CO=CHCOCF₃, p-MeOC₆H₄CO=CHCOCF₃; n = 2, 3 or 1) have been isolated. The conditions were found to be critical, involving the slow addition of an ammoniacal aqueous alcoholic solution of the β-diketone to an excess of the lanthanide nitrate solution while the pH was maintained within the range 6.0-6.5. The mass spectra of most of the chelates were obtained and were essentially similar and fluorine migration to the metal was found to occur. Although a peak for the ion M-L (M = MetL₃+) is present in the spectra, peaks for M-2L and M-3L are absent; however, peaks were obtained for the ions M-2L+ F and M-3L+2F (Met¹¹¹F2). A peak for the ion M- L+ F (Met¹¹F) was obtained when Met = Sm, Eu and Yb. The valency change from 3 to 2 occurring in the mass spectrometer in the case of samarium, europium and ytterbium is in accordance with their chemical behaviour in solution.