Study of the Mössbauer effect in europium(III) complexes

Abstract

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

The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone

“…The small experimental line width indicates one single europium species rather than multiple Eu 3+ ions in crystallographically distinct sites . Usually for Eu 3+ complexes (and other Eu 3+ solids), the range of observed isomer shifts is only within 0.8 mm s −1 and largely insensitive to the nature and number of coordinating ligands . However, the Mössbauer spectroscopic data supports overall the presence of only one Eu 3+ species in the bulk material.…”

“…The fitting of the Eu 2 PQQ 2 data further reveals an electric quadrupole splitting of Δ E Q =1.6(4) mm s −1 and an experimental line width of Γ =2.5(1) mm s −1 . The small experimental line width indicates one single europium species rather than multiple Eu 3+ ions in crystallographically distinct sites . Usually for Eu 3+ complexes (and other Eu 3+ solids), the range of observed isomer shifts is only within 0.8 mm s −1 and largely insensitive to the nature and number of coordinating ligands .…”

Mössbauer Effect Studies of the Dimer of a Bimetallic EuAl Complex

“…As shown in Table 1, the isomer shift of the '"Eu nucleus determined both from a sjngle line fitting and from a twelve-line fitting to the experimental spectra is just in the range of the values of the isomer shift of the trivalent europium [3]. Therefore, this indicates that the europium atom in the dimer of the bimetallic Eu-A1 complex is positive trivalent.…”

“…Only a few results of the Debye temperatures of europium compounds have been published [8]. However, Mossbauer studies of many complexes of europium with different organic ligands, for example carboxylic acids, have been published and the Mossbauer spectra of these complexes at room temperature can be very easily obtained [3]. From the coordination structure, the bimetallic Eu-A1 complex belongs also to the complexes of europium with carboxylic acid radicals, however, the Mossbauer effect in the dimer of the bimetallic Eu-A1 complex cannot be observed at room temperature.…”

“…, ) To whom all correspondence should be addressed. compound of europium can easily be distinguished by Mossbauer spectroscopy [3,4].…”