Europium II

Selective Reduction. In aqueous solution, europium(III) [22541 -18-0] reduction to europium(II) [16910-54-6] is carried out by treatment with amalgams or zinc, or by continuous electrolytic reduction. Photochemical reduction has also been proposed. When reduced to the divalent state, europium exhibits chemical properties similar to the alkaline-earth elements and can be selectively precipitated as a sulfate, for example. This process is highly selective and allows production of high purity europium fromlow europium content solutions (see Calcium compounds Strontiumand strontium compounds). 

Ammonium sulphide) Barium sulphide Calcium sulphide Chromium (II) sulphide Copper (II) sulphide Diantimony trisulphide Dibismuth trisulphide Dicaesium selenide Dicerium trisulphide Digold trisulphide Europium (II) sulphide Germanium (II) sulphide Iron disulphide Iron (II) sulphide Manganese (II) sulphide Mercury (II) sulphide Molybdenum (IV) sulphide... 

Butyllithium Europium (II) sulphide Dichlorodi methyl si lane... 

By means of a stopped-flow technique, Carlyle and Espenson ° ° have subjected the reaction between europium(II) and iron(III) to a detailed examination. In perchloric acid solution two processes are discerned, viz. 

Reaction between europium (III) oxide and hydrogen sulfide at 600° produces europium(III) sulfide predominately, but europium (II) sulfide is the product of reaction at higher temperatures.3 It has been found necessary to modify the previously published procedure3 in order to remove the last traces of elemental sulfur which otherwise contaminate the product. 

Europium (II) sulfide is a black powder possessing a sodium chloride lattice7 and an unknown melting point. Crystals of the sulfide have a golden hue by reflected light. The compound exhibits ferromagnetism8 with a Curie temperature of 17°K. Above this temperature, europium (II) sulfide behaves as a typical paramagnetic compound.2... 

EXAFS study on Eu2+ and Sr2+ in both solid state and aqueous solution gave coordination numbers of 8.0 for strontium(II) and 7.2 for europium(II) (228). The water exchange rate measured on the divalent europium aqua ion is the fastest ever measured by 170 NMR (Table XVI) (2). The activation volume is much more negative (—11.7 cm3 mol-1) than those determined on trivalent lanthanide aqua ions clearly indicating an a-activation mechanism which is most probably a limiting... 

Example Fluoride-ion Electrode In this particular instance the membrane essentially comprises of a single crystal of lanthanum fluoride (LaF3), usually doped with a slight trace of europium (II), Eu2+, so as to initiate the crystal defects required for establishing its electrical conductivity. Therefore, the potential developed at each surface of the membrane is finally determined by the exact status of the equilibrium ... 

Caesium selenide, 4265 Calcium polysulfide, 3942 Calcium sulfide, 3941 Cerium trisulfide, 3967 Chromium(II) sulfide, 4245 Cobalt(II) sulfide, 4218 Copper iron(II) sulfide, 4269 Copper(II) sulfide, 4285 Europium(II) sulfide, 4293... 

All lanthanide ions, with the exception of gadolinium(III) and europium(II), are likely to be relaxed by Orbach-type processes at room temperature. In fact, the f" configurations n l) of lanthanides(III) give rise to several free-ion terms that upon strong spin-orbit coupling, provide several closely spaced energy levels. Table III reports the multiplicity of the ground levels, which varies from 6 to 17, and is further split by crystal field effects. 

In dry aprotic solvents such as acetonitrile [28] with tetraethylammonium bromide as supporting electrolyte or dimethylformamide [29] with sodium perchlorate as supporting electrolyte, the ( ) / rneso ratio for pinacols rises substantially in favour of the ( )-form. Reduction of acetophenone in dimethylformamide in the presence of europium(ni) chloride leads to the ( )-pinacol only. Under these reaction conditions, europium(ii) is formed and dimerization occurs with the involvement of this ion and the ketone in a complex [30]... 

Bis(aciylonitrile)nickel(0), 2312 l,2-Bis(dichlorophosphino)ethane, 0797 Bis(trimethylsilyl) phosphonite, 2611 Bromodimethylborane, 0887 Calcium silicide, 3943 Cerimn trisulfide, 3967 Chromimn(II) acetate, 1493 Chromimn(II) oxide, 4241 Cobalt(III) nitride, 4214 Cobaltai) sulfide, 4218 Dicobalt boride, 0128 Dimethyl ethanephosphonite, 1732 Europium(II) sulfide, 4293 2-Fm-aldehyde, 1836 Indimn(II) oxide, 4641... 

The reduction to the divalent state involves samarium, europium, and ytterbium. In 1906 C. Matignon and E. Gazes obtained samarium(II) chloride by reducing the trichloride with hydrogen. In 1911, G. Urbain and F. Bourion prepared europium(II) chloride by a comparable reduction involving gydrogen, and in 1929 ytterbium(II) chloride was similarly obtained by W. Klemm and W. Schuth. 

On an industrial scale, only the reduction of europium(II) with zinc, followed by its recovery as a divalent sulfate from chloride solution is useful. In practive, it is possible to recover europium from mixtures containing only trace quantities by adding zinc, barium chloride and sulfuric acid the mixed... 

Garton, G., and D. A. Hukin Studies of some Europium (II) compounds, Third Rare Earth Conference, Clearwater (Florida), April 1963. 

In aqueous solutions, trivalent lanthanides are very stable whereas only a limited number of lanthanides exhibit a stable divalent or tetravalent state. Practically, only Ce4+and Eu2+ exist in aqueous solutions. The properties of these cations are very different from the properties of the trivalent lanthanides. For example, Ce4+ is more acidic and cerium(IV) hydroxide precipitates at pH 1. Eu2+ is less acidic and europium(II) hydroxide does not precipitate at pH 7—8.5, whereas trivalent lanthanide hydroxides do. Some industrial separations are based on these phenomena. 

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