Competitive equilibria in lanthanide trifluoromethanesulfonate solutions in propylene carbonate containing a 15-crown-5 ether

Pilloud, Francis; Bünzli, Jean‐Claude G.

doi:10.1016/s0020-1693(00)84064-5

Cited by 9 publications

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“…fluoromethanesulfonates in propylene carbonate. 14 In the case of anhydrous Ln(III) perchlorate solutions (Ln ) lanthanide) in acetonitrile (all solutions prepared were 0.05 mol dm -3 ), these authors showed that both monodentate and bidentate perchlorate anions are in the inner coordination sphere resulting in complicated equilibria between species which differ by the number and type of coordinated perchlorate anions and probably the number of coordinated acetonitrile molecules. Two changes in the average coordination number across the lanthanide series were shown to occur, one between La and Pr and the other at Gd.…”

Section: Introductionmentioning

confidence: 99%

“…As far as lanthanide(III) cation salts are concerned, few studies have been reported in nonaqueous solvents (some of which are conflicting) which suggest the presence of anion coordination to lanthanide(III) cations in these solvents with certain anions. Thus, Bünzli and co-workers − have investigated the interaction of lanthanide(III) cations and various anions in organic solvents. Using 139 La NMR and FT-IR measurements 10 these authors showed the presence of significant inner-sphere interactions between La(III) and various anions in methanol at 298 K. These interactions result in the formation of complexes of the type LaX n (3-n)+ and increase in the order Other studies carried out by Bünzli and co-workers include investigations of anhydrous solutions of lanthanide(III) perchlorates in acetonitrile, , europium perchlorate and nitrate in N , N -dimethylformamide 13 as well as lanthanide(III) trifluoromethanesulfonates in propylene carbonate .…”

Section: Introductionmentioning

confidence: 99%

“…Thus, Bünzli and co-workers − have investigated the interaction of lanthanide(III) cations and various anions in organic solvents. Using 139 La NMR and FT-IR measurements 10 these authors showed the presence of significant inner-sphere interactions between La(III) and various anions in methanol at 298 K. These interactions result in the formation of complexes of the type LaX n (3-n)+ and increase in the order Other studies carried out by Bünzli and co-workers include investigations of anhydrous solutions of lanthanide(III) perchlorates in acetonitrile, , europium perchlorate and nitrate in N , N -dimethylformamide 13 as well as lanthanide(III) trifluoromethanesulfonates in propylene carbonate . In the case of anhydrous Ln(III) perchlorate solutions (Ln = lanthanide) in acetonitrile (all solutions prepared were 0.05 mol dm -3 ), these authors showed that both monodentate and bidentate perchlorate anions are in the inner coordination sphere resulting in complicated equilibria between species which differ by the number and type of coordinated perchlorate anions and probably the number of coordinated acetonitrile molecules.…”

Section: Introductionmentioning

confidence: 99%

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Complexation of Calixarene Derivatives and Lanthanide Cations in Nonaqueous Media

Namor

Jafou

2001

J. Phys. Chem. B

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The complexing properties of two lower rim calix(4)arene derivatives, namely, 5,11,17,23-tetrakis(1,1dimethylethyl)-25,27-bis[2-(methylthio)ethoxy]-26,28-bis[2-(diethylamine)ethoxy]calix(4)arene (1a) and p-tertbutylcalix(4)arene tetradiisopropylethanoamide (1b) toward lanthanide(III), scandium, and yttrium cations in acetonitrile and in N,N-dimethylformamide at 298.15 K were investigated. 1 H NMR complexation experiments established the presence of interactions between the hydrophilic cavity of these macrocycles and these metal cations and revealed the active sites of complexation of these ligands. Conductance measurements were used to (i) establish the concentrations at which the lanthanide trifluoromethanesulfonate salts are fully dissociated 3:1 electrolytes in these solvents and (ii) determine the composition of the metal-ion complex in these solvents. Titration microcalorimetry was used to derive the thermodynamics of complexation of these macrocycles and lanthanide(III) cations in acetonitrile and N,N-dimethylformamide at 298.15 K. No reliable thermodynamic data could be obtained from classical calorimetry due to the slow kinetics observed in the complexation of these calixarene derivatives and these cations in these solvents. Stability constants of 1a were also determined by the competitive potentiometric method using the silver electrodes. Excellent agreement was found between the data derived from calorimetry and those derived by potentiometry. For all the systems investigated, the complexation process between these cations and these ligands was enthalpically controlled. Enthalpy-entropy compensation effects were observed in the complexation of 1a and the different lanthanide(III) cations in acetonitrile and in N,N-dimethylformamide, as suggested by the absence of significant variations in the Gibbs energies of complexation in each case. As far 1b is concerned, a selective behavior was observed for this ligand and the various cations in acetonitrile with the highest stabilities found for gadolinium and europium. The enthalpic and entropic contributions to the Gibbs energy associated with these processes are analyzed. Final conclusions are given.

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Section: Introductionmentioning

confidence: 99%