Europium bromide

The preparation of europium metasilicate hydrate from solutions of europium bromide and sodium metasilicate has been described.The kinetics and mechanism of the reduction of thiocyanato- and isothiocyanato-penta-amminecobalt(iii) ions by europium(ii) in acid solution have been discussed in terms of europium(ii) attack on the ambidentate bridging ligand at the end remote from the cobalt centre. The differences in the activation enthalpies for the reduction of the complexes were attributed to (a) differences in enthalpy of formation of the precursor complex Eu - X - Co (NH3)5, and (b) ease of stretching of the Co—S or Co—N bond in the precursor complex. The low-temperature Mossbauer spectrum of EUH2 suggested the covalent transfer of electron density. to the metal 6s orbital to be more marked in EuH2 than EuO. ... 

Cu2Mg 2-COPPER 1-MAGNESIUM 619 EuBr3 EUROPIUM BROMIDE 664... 

Figure 12.5 TG and DTG curves of complexes of samarium bromide (------) and europium bromide (-----) with...

Figure 12.12 TG and DTG curves of complex of europium bromide with Alanine (.3 ...

Several different compositions in the Eu-Cl-Br system have been obtained by dehydration of EUCI3 XH2O in the presence of NH4Br (Clink, 1974). As with the binary europium bromide system (cf. section 2.1), the dehydration process proceeds with complete reduction of the europium by bromide and formation of orthorhombic EuCUBrj- phases. A single crystal selected from an x = 0.46 composition has the orthorhombic (Pnma) PbCl type structure with a = 7.880, b = 4.611, c = 9.198 A (cf. section 4.4). The four- and five-coordinate anion cites are occupied respectively by Cl and Br. The R-value is minimized at x = 0.50, but the orthorhombic phase is apparently formed over a substantial portion of the EuCl2-EuBr2 system. 

Ethylamine, 338 W-Ethyl acetamide, 338 Ethyl bromide, 328 reactions of, 330 Ethyl iodide, 336 Ethylene, 346 chemical reactivity, 296 double bond in, 296 Ethylene glycol, 325 Ethyl group, 329 Europium, properties, 412 Exothermic reaction, 40, 135 Experiment, 2... 

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]... 

In 1939 Klemm and Doll [276] prepared all the halides of divalent europium and studied the magnetic characteristics of these compounds. The magnetic susceptibilities (X g) and effective moments of the fluoride, chloride, bromide and iodide are tabulated in Table 15. Except for the... 

The enantiotopic protons of the prochiral methyl groups in the iminium salt 36 exhibited distinct resonances in the presence of Eu(hfc)3 . As already discussed for achiral lanthanide S-drketonates, the system likely forms an ion pair between the organic cation and the species [Ln( S-dik)3X]. The spectrum of racemic 37, which as its bromide salt has been studied as an ionic liquid, exhibits nonequivalence in the presence of Eu(tfc)3 and Eu(hfc)3. No splitting of the resonance occurs in the presence of Eu(fod)3. In addition to the likely ion-pairing interaction of 37 with [Ln(/ -dik)3X] , rather substantial shifts of some of the OCH2 protons implied that the ether oxygen atoms also likely coordinated with the europium ion. A similar ion-paired system explains the enantiomeric discrimination observed in the spectrum of the tris(phenanthroline) complexes of Ru(II) ([Ru(phen)3]Cl2) in the presence of Eu(tfc)3 . 

Reduction in dry aprotic solvents allows the formation of ion pairs between the radical anion and a countercation. Where the cation can interact simultaneously with two radical species, dimerization favors the ( )-product because there are fewer steric interactions, in the corresponding transition state, between groups attached to the reacting radicals. Solvent and supporting electrolyte combinations that give a high yield of ( )-pinacol are acetonitrile with tetraethylammonium bromide [82], dimethylformamide with sodium perchlorate [83], and dimethylformamide with europium(III) chloride. Europium(II) is formed in the last... 

The construction of these electrodes is shown in Figure 13.12. The most successful example is the fluoride electrode. The membrane consists of a single crystal of lanthanum fluoride doped with some europium(II) to increase the conductivity of the crystal. Lanthanum fluoride is very insoluble, and this electrode exhibits Nerstian response to fluoride down to 10 M and non-Nerstian response down to 10 M (19 ppb ). This electrode has at least a 1000-fold selectivity for fluoride ion over chloride, bromide, iodide, nitrate, sulfate, monohydrogen phosphate, and bicarbonate anions and a 10-fold selectivity over hydroxide ion. Hydroxide ion appears to be the only serious interference. The pH range is limited by the formation of hydrofluoric acid at the acid end and by hydroxide ion response at the alkaline end a pH range of 4 to 9 is claimed... 

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