is a cation and L a multidentate aminopolycarboxylate ligand were prepared as described by Moeller et aL8 Compounds were prepared with Nt-(2-hydroxyethyl)ethylenediamine-NNN'-triacetic acid (hedta) , ethylenediamine-NNN'N'-tetra-acetic acid (edta), 1,2-diaminocyclohexane-NNN'N'-tetra-acetic acid (dcta) , and diethylenetriamine-NNN'N'N"-penta-acetic acid (dtpa) as ligands, and H+, K+, NH,+, or Baa+ as cations. A number of preparative methods 9-11 for europium(II1) P-diketone complexes were attempted and found t o give uncharacterisable products. The methods described by Melby et ~1 . 1 ~ and Bauer et uZ.l3 were used as a basis for the preparation of EulI1 (4-diketone complexes. Complexes of the general formula, L[Eu-(P-diketone),] where L is a cation (Na+, K+, (C,H,),N+) were prepared by mixing together stoicheiometric amounts of europic chloride, the P-diketone, and a suitable base in an ethanolic mediuni.12 The preparation and isolation of solid tris-P-diketones proved more difficult and no general method was evolved. A series of EulI1 (1,lOphenanthroline) (P-diketone) compounds were prepared by the method of Bauer et u1.13 Other 1,lO-phenanthroline complexes of EulI1 were prepared as described by Hart et a1.14 and Sinha et uZ.15 ~6~17

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Mossbauer spectroscopy has been used to observe the production of an 'anomalous' charge state, U ~E U ~+ , following the electron capture decay of 151GdS+ incorporated in Erz(Cz04)3, 10H20.

Mossbauer spectra of europic oxide show a single absorption peak which is both broad and asymmetric as a result of unresolved quadrupole splitting. Attempts to fit such spectra to a single Lorentzian peak have been found to be unsatisfactory. A more satisfactory analysis has been obtained by taking quadrupole splitting into account. The effects of prior heat treatment of europic oxide on the Mossbauer spectra have been investigated, and it is concluded that observed variations in isomer shift are not attributable to the cubic-monoclinic phase transition.IN the course of a study of the isomer shift of europic similar magnitude have been reported by Gerth et aZ.2 oxide with respect to europic fluoride it was observed for the isomer shift at room temperature of cubic that the isomer shift varied from sample to sample by europic oxide relative to monoclinic europic oxide. as much as 0-2 mm s-l, the largest deviation from the Deeney et aL3 observed a variation of 0-25 mm s-l in average value occurring with an Eu,O, sample isotopically enriched in 151Eu (99.15% 151Eu).

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