Thermodynamics of lanthanide

L. R. Morss, K. L. Nash, D. D. Ensor. Thermodynamics of Lanthanide and Uranyl Complexes with Tetrahydrofuran-2,3,4,5-tetracarboxylicAcid (THFTCA). J. Chem. Soc., Dalton Trans. 2000, 285-291. 

Liu, Y., Zhang, H. Y., Bai, X. P., Wada, T., and Inoue, Y. (2000) Molecular design of crown ethers. 21. Synthesis of novel double-armed benzo-15-crown-5 lariats and their complexation thermodynamics with light lanthanoid nitrates in acetonitrile, J. Org. Chem. 65, 7105-7109 see also Danil de Namor, A. F. D., Chahine, S., Jafou, O., and Baron, K. (2003) Solution thermodynamics of lanthanide-cryptand 222 complexation processes, J. Coord. Chem 56, 1245-1255 Israeli, Y., Bonal, C., Detellier, C., Morel, J. P., and Morel-Desrosiers, N. (2002) Complexation of the La(III) cation by p-sulfonatocalix[4]arene - A La-139 NMR study, Canad. J. Chem. 80, 163-168. 

Studies on the thermodynamics of lanthanide complex formation with ligands like ethylenediamine (en) and diethylenetriamine (dien) in acetonitrile to form [M(en) ]31... 

Choppin, GR. (1985) Thermodynamics of lanthanide-organic ligand complexes. Journal of the Less-Common Metals, 112, 193-205. 

Lanthanide (III) Oxides. The lanthanide(III) oxides will be used to illustrate the present breadth of our most extensive knowledge of the chemical thermodynamics of lanthanide compounds. Cryogenic heat capacities of hexagonal (III) lanthanum, neodymium, and samarium oxides, together with those of cubic (III) oxides of gadolinium, dysprosium, holmium, erbium, and ytterbium, have been reported (90, 91, 195). In addition, those of thulium, lutetium, and a composition approaching that of cerium (III) oxide have also been determined, and five well-characterized compositions between PrOi.714 and PrOi.833 are currently under study (J93). 

Thermodynamics of lanthanide(III) complexation in nonaqueous solvents 12CCR328. 

Nitridoborates of lanthanum and the lanthanides were obtained from reactions of lanthanide metal or lanthanide metal nitride with layer-like (a-)BN at elevated temperatures (3>1200°C). These reactions require elaborated techniques in the inert gas sample-handling and the use of efficient heating sources, such as induction heating. Only some compounds remain stable in this high-temperature segment, and the yields of such reactions are often limited due to the competing stability of binary phases, allowing only the most (thermodynamically) stable compounds to exist. 

Figure 7.10 Thermodynamic data (b)-(d) needed in analysis of the enthalpy of formation of the binary lanthanide metal compounds given in (a), (b) Sum of first, second and third ionization enthalpies of lanthanide metals (c) atomization enthalpy of lanthanide metals (d) derived lattice enthalpy of lanthanide trichlorides.

This expression has been written in terms of concentration if activity coefficients sue known or estimated, then a thermodynamically ideal solubility product may be obtained from the Emalogous product of ionic activities. As the concentration of ions in solutions of lanthanide fluorides is low, the concentration and activity solubility products will not differ markedly, although activity coefficients for these salts of 3 + cations are significantly less than unity even in such dilute solutions (4a). 

We have considered typical examples of lanthanide and actinide solvent extraction by chelate formation, involving complexes with citric acid and with TTA, to prove that the labelling of a stable element by one of its radioactive isotopes can help to produce accurate data on the stability constants for complex formation. The method is applicable to elements with radioisotopes having a half-life allowing an ion concentration of 10 6m or less. Other methods of partition such as radiopolarography and radio-coulometry also result in accurate thermodynamical data when the same procedure of labelling is used (29). 

Charbonnel, M.C., Daldon, M., Berthon, C., Madic, C., Moulin, C. 1999. Extraction of lanthanides(III) and actinides(IH) by A, A -substituted malonamides Thermodynamic and kinetic data. ISEC 99 Conference on Solvent Extraction for the 21st Century, July, Barcelona, Spain. 

This volume of the Handbook illustrates the rich variety of topics covered by rare earth science. Three chapters are devoted to the description of solid state compounds skutteru-dites (Chapter 211), rare earth-antimony systems (Chapter 212), and rare earth-manganese perovskites (Chapter 214). Two other reviews deal with solid state properties one contribution includes information on existing thermodynamic data of lanthanide trihalides (Chapter 213) while the other one describes optical properties of rare earth compounds under pressure (Chapter 217). Finally, two chapters focus on solution chemistry. The state of the art in unraveling solution structure of lanthanide-containing coordination compounds by paramagnetic nuclear magnetic resonance is outlined in Chapter 215. The potential of time-resolved, laser-induced emission spectroscopy for the analysis of lanthanide and actinide solutions is presented and critically discussed in Chapter 216. 

Lanthanide hydride derivatives are commonly synthesized by hydrogenol-ysis of lanthanide alkyl complexes [212], In order to further exploit the thermodynamic stability of the Al-N bond dizsobutylaluminum hydride (DIBAH), a common cocatalyst in diene polymerization mixtures and well-established reducing agent in organic synthesis, was used in the hydrogenol-... 

It is clear that both the thermodynamic and spectroscopic approaches agree well with respect to the estimation of redox potentials and stabilities of lanthanides in different oxidation states. 

Choppin [24] examined some aspects of lanthanide-organic ligand interaction in aqueous solutions. An interpretation of thermodynamic parameters (AG, AH and AS) of complexation have been given in terms of hydration, inner versus outer sphere character, stability vs. chelate ring size and ligand charge polarization. 

The thermodynamic parameters (i.e.) the enthalpy and entropy values showed the formation of inner-sphere chloro complexes in the case of all the lanthanides. The enthalpies for the formation of monobromo complexes of lanthanides are also positive but smaller in magnitude than the corresponding chloro complexes. The complex formation enthalpies follow the sequence A//°(C1) > A//°(Br) > A//°(I) which is unusual for hard metal(III) ions. 

The thermodynamic parameters of the thiocyanato complexes are similar to those of lanthanide bromo complexes and the latter are outer-sphere complexes in DMF. Contrary to this 89Y NMR spectra suggest an inner-sphere Y(III)-NCS complex. 

The activation parameters for both acid-dependent and acid-independent pathways are given in Table 7.16. The low enthalpy of activation and a large negative entropy of activation for the self-dissociation pathway may well be due to a rate-determining step of slow distortion of the complex to give an active intermediate. The AH values for the acid-catalyzed pathway are much smaller than the values of lanthanide complexes with EDTA, CyDTA and MEDTA indicating lower thermodynamic stability of the K21DA complexes of lanthanides [73]. 

In aqueous solutions, lanthanide(III) ions are coordinated by water molecules. The hydration sphere of the lanthanide ions plays a vital role in the chemistry of the ion and also in several biochemical reactions involving isomorphous calcium(II) substitution reactions. The interpretation of the absorption spectra of lanthanide(III) ions in aqueous media is difficult because of the variability of the coordination number of the aquo ions along the lanthanide series. Kinetic and thermodynamic studies [206-210] on the lanthanide aquo systems led to the conclusion that the lighter lanthanides have a coordination number of 9, heavy lanthanides are octacoordinated and the middle members exist in a equilibrium mixture of octa and nonacoordinated aquo ions. 

The thermodynamic stability of lanthanide complexes with inorganic ligands OH- and F increases slightly with increase in atomic number. The formation constants for MOH2+ and MF2+ formation... 

Figure 1.14 The relationship between the atomic numher of lanthanides and thermodynamic functions (Kex, AH, AZ°, and AS°) from the exaction system consisting of 2-ethyl hexyl mono(2-ethyl hexyl) ester phosphinate in a dodecane solution [14]. (Reprinted from E.X. Ma, X.M. Yan, S.Y. Wang, et al., The extraction chemistry of tanthanides with 2-ethyl-hexyle mono (2-ethyl-hexyle) phosphinate oxide, Scientia Sinica B Chemistry (in Chinese), 5, 565-573, 1981, with permission from Science in China Press.)...

Kremer, C., Torres, J., Dominguezb, S., and Mederos, A. (2005) Structure and thermodynamic stability of lanthanide complexes with amino acids and peptides. Coordination Chemistry Reviews, 249, 567-590. 

Retention of Rohrschneider-McReynolds standards of selected chiral alcohols and ketones was measured to determine the thermodynamic selectivity parameters of stationary phases containing (- -)-61 (M = Pr, Eu, Dy, Er, Yb, n = 3, R = Mef) dissolved in poly(dimethylsiloxane) . Separation of selected racemic alcohols and ketones was achieved and the determined values of thermodynamic enantioselectivity were correlated with the molecular structure of the solutes studied. The decrease of the ionic radius of lanthanides induces greater increase of complexation efficiency for the alcohols than for the ketone coordination complexes. The selectivity of the studied stationary phases follows a common trend which is rationalized in terms of opposing electronic and steric effects of the Lewis acid-base interactions between the selected alcohols, ketones and lanthanide chelates. The retention of over fifty solutes on five stationary phases containing 61 (M = Pr, Eu, Dy, Er, Yb, n = 3, R = Mef) dissolved in polydimethylsiloxane were later measured ". The initial motivation for this work was to explore the utility of a solvation parameter model proposed and developed by Abraham and coworkers for complexing stationary phases containing metal coordination centers. Linear solvation... 

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