Lanthanide Halides Research Articles

Fluorescence spectra of matrix-isolated praseodymium triodide molecules

Fluorescence spectra of PrI 3 molecules isolated in Ar and Xe matrices have been measured for the first time. More than 40 transitions have been measured using Hg excitation and have been assigned to transitions within the 4 f 2 configuration. An interpretation of the spectrum is given based on an energy level diagram calculated by adopting an intermediate coupling model and considering electronic repulsion, spin-orbit and “crystal field” interactions. The “crystal field” is assumed to arise from iodide ions located at the points of an equilateral triangle giving the PrI 3 molecule D 3 h symmetry. Results of least-squares refinement calculations for the PrI 3 molecule give the values A 2 0 = −282.5 cm −1 ; A 4 0 = 36.1 cm −1 ; A 6 0 = 26.8 cm −1 ; A 6 6 = 231.7 cm −1 . The effect on the parametric values in going from ninefold coordination (Pr 3+ in LaCl 3 crystals) to threefold coordination (PrI 3 molecules) is calculated using the point charge model, and compared with the experimental results. It is suggested that the matrix isolated rare-earth halide molecules are useful systems for studying matrix perturbation effects and for detailed m.o. calculations to fix the splitting parameters.

Force-constant models of lattice vibrations in rare-earth halides

Various harmonic force models are used to fit experimental k = 0 lattice vibration frequencies in LaCl 3, CeCl 3, PrCl 3 and LaBr 3. It is shown that a very approximate model using only two parameters gives a reasonable fit to six or more frequencies. This is not greatly improved by the use of more sophisticated models. The k = 0 eigenvector for a particular choice of force constants is also given.

Force-constant models of lattice vibrations in rare-earth halides

The polymeric complexes S4N4H4 with SiCl4 were prepared crystallized, and their EPR-spectra have been investigated to determine g, u, E, and the characteristic - x plots.

Low-Temperature Optical Absorption of Americium Halides

Absorption spectra at low temperatures are reported for AmCl3, AmBr3, and AmI3. Bathochromic shifts have been generally observed in the series from the chloride to the iodide. These shifts are comparable to those observed in lanthanide halides. Hypersensitive transitions have been observed in AmI3. A number of new assignments of excited levels of Am(III) are proposed on the basis of intensity calculations. Electrostatic, spin–orbit, and configuration-interaction parameters were obtained by direct diagonalization and least-squares fitting to 29 observed levels for AmCl3. The parameter values in cm−1 are: E1 = 3582.8, E2 = 17.276, E3 = 334.30, ξ5f = 2593.3, α = 21.634, β = − 158.48, γ = 1240.4.

Rare earth metal-metal halide systems XII. The thulium-thulium(III) chloride system. Thulium(II) chloride and a series of intermediate phases

Thermal analysis, equilibration, and X-ray data are reported for the condensed TmCl 3-Tm system. Thulium(II) chloride melts congruently at 718 ± 3 °C and is isostructural with DyCl 2 and YbCl 2 with a 0 = 6.55, b 0 = 6.68, c 0 = 6.93 A ̊ , all ± 0.02 A ̊ . The dichloride dissolves in water to give a short-lived, bordeaux-red color. Thermal analysis data give evidence for the presence of about nine intermediate compounds between TmCl 2.04 and about TmCl 2.12. Their apparent peritectic interconversions at 662 °–585 °C are rapid on both heating and cooling, and a close relationship between these and the parent TmCl 2 structure is indicated by their powder patterns. The compounds may be considered as the ordered phases which derive from a hypothetical nonstoichiometric region.

MECHANISMS OF ENERGY TRANSPORT BETWEEN RARE-EARTH IONS

Recently a series of experiments on the EPR of pairs of coupled rare-earth ions in the light rare-earth halides have been reported. From these experiments it is possible to obtain very detailed information about the mechanisms responsible for nonradiative energy transfer. In particular, it is shown that superexchange is much more effective than normally assumed both in terms of selection rules and range.

Infrared spectra of terpyridyl-rare earth halide complexes (650-80 cm −1)

Infrared studies have been made on several mono and bis terpyridyl—rare earth (III) halide complexes. The results obtained in the 650-80 cm −1 region are presented. Assignments for the rare earth metal—chloride and metal—bromide stretching vibrations are made. The results do not allow assignments to be made for metal—nitrogen vibrations.

Infrared spectra of complexes of 8-aminoquinoline with lanthanide halides

Infrared spectra of complexes of 8-aminoquinoline with lanthanide halides

Electron transfer spectra of some solid lanthanide(III) complexes

Electron transfer spectra are reported for the compounds LnPO4,Ln2(CO3)3,3H2O,Ln2(oxalate)3,10H2O, and several compounds containing sulphate or halide ions (Ln = Sm, Eu, and Yb). The shifts in the band positions correlate with the number of co-ordinated ligands. All oxygen donors of the type AOnx–(sulphate, selenate, etc.) show similar optical electronegativities. The ytterbium spectra are sometimes difficult to correlate with those of the other metals because of changes in co-ordination sphere. Electron transfer spectra of lanthanide halides do not always show the same halide dependence as transition-metal spectra.

Preparation of anhydrous single crystals of rare-earth halides

Anhydrous rare-earth halides are prepared by the conversion of the rare-earth oxide to the halide by means of its reaction with the appropriate ammonium halide. Without transfer from the reaction vessel, the halide is melted, then crystallized by slow cooling. The resulting solid usually contains single crystals large enough to permit spectroscopic studies of the compounds.

THE HEATS OF FUSION AND TRANSITION OF ALKALINE EARTH AND RARE EARTH METAL HALIDES

The heats of fusion of fifteen rare earth and alkaline earth halides were measured by means of a copper block drop calorimeter. The salts and their heats of fusion in kcal mole/sup -1/ are LaCl/sub 3/, 13.0; PrCl/sub 3/, 12.1; NdCl/sub 3/, 12.0; C eI/sub 3/, 12.4; PrI/sub 3/, 12.7; NdI/sub 3/, 9.7; CaCl/sub 2/, 6.78; CaBr/sub 2/, 6.95; C aI/sub 2/, 10.0; SrCl/sub 2/, 3.88; SrBr/sub 2/ 2.50; SrI/sub 2/, 4.70; BaCI/sub 2/, 3.90; BaBr/sub 2/, 7.63; and BaI/sub 2/, 6.34. The four salts which showed a transition, their temperatures of transition in deg K and their heats of transition in kcal mole/sup -1/ are Ndl/sub 3/, 847, 3.4; SrCl/sub 2/, 1003, 1.65; SrBr/sub 2/, 918, 2.90; and BaCl/sub 2/, 1193, 4.1O. The high temperature forms of SrBr/sub 2/ and BaCl/sub 2/ are believed to have the fluorite type of stracture characterized similarly as in CaF/sub 2/ and SrCl/ sub 2/ by an unusually low entropy of fusion, probably because a high degree of disorder occurs in that structure at elevated temperatures. (auth)

Flame spectra of the rare-earth elements

The rare-earth elements, including scandium and yttrium, emit intense line spectra when absolute ethanol solutions of rare-earth halide or perchlorate salts are aspirated into fuel-rich, oxy-acetylene flames. Recordings of the spectra are given, along with the exact wavelengths of about 1200 of the strongest lines. A discussion of the analytical utility of the stronger lines and excitation processes which may account for the appearance of these spectra is included.

Preparation of anhydrous lanthanide halides, especially iodides

A general method is described which can be used to synthesize nearly all the lanthanide halides in high purity and good yield. It involves heating in vacuo, a molecularly dispersed mixture of hydrated lanthanide halide with the proper ammonium halide until the water and ammonium halide are expelled to leave pure, anhydrous lanthanide halide. All tri-halides except the iodides of samarium and europium are obtained. These are obtained as di-halides. Optimum condition for synthesis are discussed. The procedure is the only one which has been reported for preparing pure anhydrous iodides with relatively simple apparatus and technique.

Electrodeless Discharge Tubes Containing Rare Earth and Heavy Element Halides*

A method is described for the preparation of electrodeless discharge tubes containing very pure rare earth and heavy element halides. Successful tubes have been prepared using Nd, Pm, Tb, U, Pu, Np, and Am. The effect of changing vapor pressure of the metal in the discharge is discussed and representative spectra shown.

The Vapor Phase Hydrolysis of the Rare Earth Halides. II. Heat and Free Energy of the Reactions: SmCl3(s) + H2O(g) = SmOCl(s) + 2HCl(g) and GdCl3(s) + H2O(g) = GdOCl(s) + 2HCl(g)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Vapor Phase Hydrolysis of the Rare Earth Halides. II. Heat and Free Energy of the Reactions: SmCl3(s) + H2O(g) = SmOCl(s) + 2HCl(g) and GdCl3(s) + H2O(g) = GdOCl(s) + 2HCl(g)C. W. Koch and B. B. CunninghamCite this: J. Am. Chem. Soc. 1953, 75, 4, 796–797Publication Date (Print):February 1, 1953Publication History Published online1 May 2002Published inissue 1 February 1953https://doi.org/10.1021/ja01100a010RIGHTS & PERMISSIONSArticle Views131Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (214 KB) Get e-Alerts Get e-Alerts

Conductances, Transference Numbers and Activity Coefficients of Aqueous Solutions of Some Rare Earth Halides at 25°1

Conductances, Transference Numbers and Activity Coefficients of Aqueous Solutions of Some Rare Earth Halides at 25°¹

The Vapor Phase Hydrolysis of Rare Earth Halides. I. Heat and Free Energy of the Reaction: LaCl3(s) + H2O(g) = LaOCl(s) + 2HCl(g)1

The Vapor Phase Hydrolysis of Rare Earth Halides. I. Heat and Free Energy of the Reaction: LaCl₃(s) + H₂O(g) = LaOCl(s) + 2HCl(g)¹

Crystallography of some rare earth halides

Crystallography of some rare earth halides