Ultrasonic absorption in aqueous salts of the lanthanides

Fay, D.; Litchinsky, Daniel.; Purdie, Neil

doi:10.1021/j100723a012

Cited by 79 publications

(51 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The enthalpy and entropy values for the lanthanide and actinide monosulphate formation are very similar and positive. From this it was concluded that an appreciable amount of inner sphere complexation was present 28 • Earlier, a study by infra-red spectroscopy had led to an estimate of only 12 per cent inner sphere formation 29 . However, spectral data 8 • 30 as well as the rates of formation of the monosulphate complexes studied by uhrasonie absorption 31 are in agreement with the interpretation from the thermodynamic data that the complexes are predominantly inner sphere in nature.…”

Section: Coordination Numbersupporting

confidence: 79%

Structure and thermodynamics of lanthanide and actinide complexes in solution

Choppin¹

1971

Pure and Applied Chemistry

143

View full text Add to dashboard Cite

Several questions of importance in the study of lanthanide and actinide coordination compounds are reviewed. There is considerable evidence that in aqueous solution the primary coordination number is nine for the ions La(m) through Nd(m) and eight for the ions heavier than Gd(m). While it seems that some degree of covalency exists in the metal-ligand bonding a model of electrostatic bonding seems satisfactory for explaining the structure and formation of the complexes. The dehydration of the lanthanide ions upon complexation largdy determines the enthalpy and entropy data. However, there seems to be a compensation effect in the hydration parts of those terms such that the free energy changes seem to reflect the metal-ligand reaction unobscured by hydration factors. A number of individual inorganic and organic Iigand systems are reviewed from these viewpoints.The lanthanide and actinide elements constitute two families of metals which often exhibit very similar chemical behaviour. This similarity is most easily observed with the cations in oxidation state m, the most common one for all the elements of the lanthanide series and for the transplutonium elements of the actinide series. This paper reviews the present state of understanding of the complexes formed in aqueous solution by the trivalent ions of these two families ofelements.The coordination chemistry of these elements has been studied neither as intensively nor as extensively as that of the transition metal ions. One reason for this is that these elements have been less available generally than the transition metal elements. Although they are fairly abundant, a Iack of industrial application until a relatively few years ago caused many of the lanthanide elements to be fairly expensive. Increased interest in the use of these elements in phosphors and lasersandas catalysts as weil as improvements in the methods of separation has caused a substantial reduction in their cost. The availability of the transuranium elements of the actinide series was limited to a few nuclear energy laboratories where greater emphasis was placed on research of either a more nuclear or more applied nature. This latter situation has changed as the transplutonium programme of the US Atomic Energy Commission has resulted in production of relatively large amounts of the elements as heavy as californium (Z = 98). However, the 23 Unauthenticated Download Date | 5/10/18 2:05 PM

show abstract

Section: Coordination Numbersupporting

confidence: 79%

Structure and thermodynamics of lanthanide and actinide complexes in solution

Choppin¹

1971

Pure and Applied Chemistry

143

View full text Add to dashboard Cite

show abstract

“…[8][9][10][11] The rates of complex formation with sulfate and acetate ions also show a maximum at about samarium. [12,13] Liquidliquid extraction experiments indicated that instead of dividing the trivalent lanthanoidA C H T U N G T R E N N U N G (III) ions into two octads of elements with gadolinium common to both, four tetrads intersecting at neodymium/prometium, gadolinium, and holmium/erbium could better correlate with several physicochemical properties. [14] This tetrad effect is also discerned, for example, in the stability constants of the EDTA complexes in aqueous solution (see Figure S1 in the Supporting Information).…”

Section: Lua C H T U N G T R E N N U N G (H 2 O) 82 ]A C H T U N G Tmentioning

confidence: 99%

Hydration of Lanthanoid(III) Ions in Aqueous Solution and Crystalline Hydrates Studied by EXAFS Spectroscopy and Crystallography: The Myth of the “Gadolinium Break”

Persson

D’Angelo

Panfilis

et al. 2008

Chemistry A European J

277

314

View full text Add to dashboard Cite

The structures of the hydrated lanthanoid(III) ions including lanthanum(III) have been characterized in aqueous solution and in the solid trifluoromethanesulfonate salts by extended X-ray absorption fine structure (EXAFS) spectroscopy. At ambient temperature the water oxygen atoms appear as a tricapped trigonal prism around the lanthanoid(III) ions in the solid nonaaqualanthanoid(III) trifluoromethanesulfonates. Water deficiency in the capping positions for the smallest ions starts at Ho and increases with increasing atomic number in the [Ln(H(2)O)(9-x)](CF(3)SO(3))(3) compounds with x=0.8 at Lu. The crystal structures of [Ho(H(2)O)(8.91)](CF(3)SO(3))(3) and [Lu(H(2)O)(8.2)](CF(3)SO(3))(3) were re-determined by X-ray crystallography at room temperature, and the latter also at 100 K after a phase-transition at about 190 K. The very similar Ln K- and L(3)-edge EXAFS spectra of each solid compound and its aqueous solution indicate indistinguishable structures of the hydrated lanthanoid(III) ions in aqueous solution and in the hydrated trifluoromethanesulfonate salt. The mean Ln--O bond lengths obtained from the EXAFS spectra for the largest ions, La-Nd, agree with estimates from the tabulated ionic radii for ninefold coordination but become shorter than expected starting at samarium. The deviation increases gradually with increasing atomic number, reaches the mean Ln-O bond length expected for eightfold coordination at Ho, and increases further for the smallest lanthanoid(III) ions, Er-Lu, which have an increasing water deficit. The low-temperature crystal structure of [Lu(H(2)O)(8.2)](CF(3)SO(3))(3) shows one strongly bound capping water molecule (Lu-O 2.395(4) A) and two more distant capping sites corresponding to Lu-O at 2.56(1) A, with occupancy factors of 0.58(1) and 0.59(1). There is no indication of a sudden change in hydration number, as proposed in the "gadolinium break" hypothesis.

show abstract

“…From these data a K 3 -value was determined at 0.90 AE 0.1 at 23 C and it appears that the Raman derived K 3 value is comparable to the UA-values considering the uncertainty of the data from the UA measurements. 19,20,34,35 Temperature dependent measurements. A 0.0094 mol L…”

Section: àmentioning

confidence: 99%

“…5,6 The hydration sphere of La 3+ (aq) is labile and a water-exchange rate constant k ex at 25 C was given at $2 Â 10 8 s À1 ‡ (estimated from H 2 O-SO 4 2À interchange rates) and a water residence time s ¼ $5 ns follows. 19,20 Because of the labile coordination sphere for La 3+ there is the possibility of a counterion (anion) coordination replacing water from the coordination polyhedron.…”

mentioning

confidence: 99%

A Raman spectroscopic investigation of speciation in La₂(SO₄)₃(aq)

Rudolph

Irmer

2015

RSC Adv.

View full text Add to dashboard Cite

Raman spectroscopic measurements have been made of aqueous solutions of La(ClO 4 ) 3 , La 2 (SO 4 ) 3 , and Na 2 SO 4 in water and heavy water, in the terahertz frequency region (40-1400 cm À1) and down to low , the n 1 -SO 4 2À band in La 2 (SO 4 ) 3 (aq) showed systematic differences from that in Na 2 SO 4 (aq). This is consistent with a n 1 -SO 4 2À band at 983.3 cm À1 that can be assigned to the existence of an outer-sphere complex (OSCs). The observed change of the degree of sulfato-complex formation with dilution reflects the stepwise sulfato-complex formation. A K 3 -value has been determined at 0.9 of the equilibrium between OSC and ISC.

show abstract

Ultrasonic absorption in aqueous salts of the lanthanides

Cited by 79 publications

References 1 publication

Structure and thermodynamics of lanthanide and actinide complexes in solution

Structure and thermodynamics of lanthanide and actinide complexes in solution

Hydration of Lanthanoid(III) Ions in Aqueous Solution and Crystalline Hydrates Studied by EXAFS Spectroscopy and Crystallography: The Myth of the “Gadolinium Break”

A Raman spectroscopic investigation of speciation in La₂(SO₄)₃(aq)

Contact Info

Product

Resources

About

Ultrasonic absorption in aqueous salts of the lanthanides

Cited by 79 publications

References 1 publication

Structure and thermodynamics of lanthanide and actinide complexes in solution

Structure and thermodynamics of lanthanide and actinide complexes in solution

Hydration of Lanthanoid(III) Ions in Aqueous Solution and Crystalline Hydrates Studied by EXAFS Spectroscopy and Crystallography: The Myth of the “Gadolinium Break”

A Raman spectroscopic investigation of speciation in La2(SO4)3(aq)

Contact Info

Product

Resources

About

A Raman spectroscopic investigation of speciation in La₂(SO₄)₃(aq)