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  • 1
    Electronic Resource
    Electronic Resource
    NMR studies of preferential solvation of sodium cation in mixtures of N-methylformamide with water and some nonaqueous solvents (1989)
    Springer
    Journal of solution chemistry 18 (1989), S. 759-770 
    Details
    ISSN: 1572-8927
    Keywords: N-methylformamide ; nonaqueous solvents ; preferential solvation ; isosolvation point ; sodium-23 NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sodium-23 NMR chemical shifts and linewidths have been measured for 0.1M NaClO4 in binary mixtures of N-methylformamide (NMF) with a series of other solvents, as a function of the solvent mole fraction. The relative solvent composition at the isosolvation point, the mid-value of the Na-23 chemical shift between those measured in the respective pure solvents, reveals preferential solvation of the sodium cation in many cases. The isosolvation composition correlates well with the relative solvating abilities of the two solvents-as characterized by their donicities-provided that the cation-solvent interactions are of the ‘hard-hard’ type and that they are not complicated by interionic interactions. The variation in the electric field gradient around the sodium nucleus, as the composition of the solvent changes, results in broadening of the resonance line. Maximum broadening occurs close to the solvent mole fraction corresponding to the isosolvation point.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00651808
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopic studies of ionic solvation. XX. Cesium-133 NMR study of cesium salts in different solvents (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 337-348 
    Details
    ISSN: 1572-8927
    Keywords: Cesium-133 NMR chemical shifts ; nonaqueous solvents ; solvation ; ion pairs ; ion-pair formation constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cesium-133 chemical shifts were measured in a number of solvents as a function of salt concentration and of the counterion. Infinite-dilution chemical shifts (vs. aqueous Cs+ ion at infinite dilution) ranged from +59.8 ppm for nitromethane solutions to −29.4 ppm for pyridine. In general, the magnitude of the downfield chemical shift reflected the donor ability of the solvents. Ion-pair formation constants were calculated from the concentration dependences of133Cs chemical shifts in several nonaqueous solvents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647048
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  • 3
    Electronic Resource
    Electronic Resource
    Study of monensin complexes with monovalent metal lons in anhydrous methanol solutions (1978)
    Springer
    Journal of solution chemistry 7 (1978), S. 357-372 
    Details
    ISSN: 1572-8927
    Keywords: Monensin ; antibiotic ionophores ; alkali complexes ; thallium(l) complex ; Silver(l) complex ; stability constants ; entropy of complexation ; enthalpy of complexation ; nonaqueous solvents ; potentiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Potentiometric and cyclo-voltammetric studies have been carried out on monensin anion (Mon−) complexes with the alkali ions as well as with Tl+ and Ag+ in absolute methanol solutions. The log Kf values obtained for the complexity constants and corrected for the activity effects are: Li+, 3.3±0.1; Na+, 6.72±0.05; K+, 5.18±0.05; Rb+, 4.58±0.05; Cs+, 3.75±0.05; Tl+, 5.31±0.05; Ag+, 8.2±0.2. It is seen that for the alkali, the most stable complex is formed with Na+. The enthalpy and entropy of complexation with the sodium ion were found to be ΔHo=−5.47±0.24 kcal-mole−1 and ΔSo=+12.4±0.7 e.u. The complex, therefore, is enthalpy and entropy stabilized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00662896
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  • 4
    Electronic Resource
    Electronic Resource
    Far-infrared and Raman study of lithium and sodium cryptates in nonaqueous solvents (1975)
    Springer
    Journal of solution chemistry 4 (1975), S. 599-608 
    Details
    ISSN: 1572-8927
    Keywords: Cryptates ; alkali metal complexes ; infrared spectra ; Raman spectra ; nonaqueous solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Far-infrared spectra of sodium and lithium cryptates were observed in several nonaqueous solvents. The spectra are characterized by a broad band whose frequency is independent of the solvent or of the anion and which is assigned to the vibration of the cation in the cryptand cavity. The band frequencies were 234±2, 218±1, 243±3, and 348±1 cm−1 for Na+-C222, Na+-C221, Li+-C221, and Li+-C211 cryptates, respectively. These bands were found to be Raman-inactive, indicating that the cation-ligand interaction is very largely electrostatic in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00643382
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  • 5
    Electronic Resource
    Electronic Resource
    Spectroscopic studies of ionic solvation. XXI. A raman, infrared, and NMR study of sodium perchlorate solutions in nonaqueous solvents (1976)
    Springer
    Journal of solution chemistry 5 (1976), S. 653-665 
    Details
    ISSN: 1572-8927
    Keywords: Sodium-23 NMR ; chlorine-35 NMR ; intrared ; Raman ; perchlorate ion ; ion pairs ; nonaqueous solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sodium perchlorate solutions in several nonaqueous solvents were examined by23Na,35Cl-NMR, infrared, and Raman spectroscopic techniques. The formation of contact ion pairs lowers the symmetry of ClO 4 − ion from Td to C3v or C2v provided that the interaction is fairly strong. This was manifested for NaClO4 solutions in acetonitrile, tetrahydrofuran, and pyridine. Combination of the vibrational measurements with NMR shows that in the above three cases the anion-cation interactions are quite strong. Sodium-23 NMR studies confirm the above results and, being a more sensitive technique, also indicates weak cation-anion interaction in propylene carbonate, formic acid, acetone, methanol, ethanol, dimethyl sulfoxide, and water. In all solvents the23Na resonance shifts upfield with increasing concentration of NaClO4, indicating that the replacement of solvent by ClO 4 − ion decreases electron density around the cation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648223
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  • 6
    Electronic Resource
    Electronic Resource
    Lithium-7, sodium-23, and cesium-133 NMR and far infrared study of alkali complexes with C222-dilactam in various solvents (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 299-307 
    Details
    ISSN: 1572-8927
    Keywords: Lithium-7 NMR ; sodium-23 NMR ; cesium-133 NMR ; far infrared ; alkali complexes ; cryptates ; formation constants ; nonaqueous solvents ; membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nuclear magnetic resonances of alkali nuclei,7Li,23Na, and133Cs, as well as far infrared measurements are used to study alkali complexes of a bicyclic diazapolyoxa ligand—the dilactam of cryptand C222. Measurements were carried out in pyridine, tetrahydrofuran, acetonitrile, nitromethane, dimethylformamide, and aqueous solutions. The complexing ability of the dilactam is similar to, but weaker than, that of the cryptand C222. The limiting chemical shifts of the complexed cations were solvent-dependent, indicating incomplete enclosure of the cation by the ligand. Formation constants of Li+ and Cs+ complexes were calculated from the chemical-shift dependence on the ligand/metal ion mole ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647044
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of stability constants of cesium [2]-cryptand complexes in nonaqueous solvents by cesium-133 NMR (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 771-778 
    Details
    ISSN: 1572-8927
    Keywords: Cesium-133 NMR ; cryptates ; alkali complexes ; stability constants ; nonaqueous solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cesium complexes with four diazapolyoxamacrobicyclic ligands ([2]-cryptands), C211, C221, C222, and C222B, were investigated in pyridine, acetone, propylene carbonate, N,N-dimethylformamide, acetonitrile, and dimethyl sulfoxide solutions by cesium-133 NMR. The relative stabilities of the complexes are in the order Cs+·C221≥Cs+·C222〉Cs+·C222B≫Cs+·C211. The formation constants are strongly influenced by the solvating abilities of the solvents. The NMR data and stereochemical considerations indicate that in the C222−Cs+ system there is an equilibrium between “exclusive” and “inclusive” conformations of the complex. The other three ligands must form only the “exclusive” complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650453
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  • 8
    Electronic Resource
    Electronic Resource
    Magnesium-25 NMR studies of magnesium salts and complexes in nonaqueous solvents (1979)
    Springer
    Journal of solution chemistry 8 (1979), S. 283-291 
    Details
    ISSN: 1572-8927
    Keywords: Magnesium-25. NMR ; magnesium salts ; nonaqueous solvents ; macrocyclic ligands ; crowns ; cryptands ; phosphonoacetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Magnesium-25 NMR measurements were carried out on aqueous and non-aqueous solutions of magnesium salts. In the former case the25Mg resonance frequency was independent of the concentration or of the counterion. In nonaqueous solvents, however, the resonance frequency was dependent on the solvent, the concentration, and on the nature of the counterion, indicating some cation-anion interactions. Measurements on Mg2+—phosphonoacetic acid mixtures in aqueous solutions gave strong indications of complexation. Only inconclusive evidence was obtained on the complexation of Mg2+ by macro-bicyclic cryptand C211 in methanol solutions, and no evidence of complexation was obtained with macrocycle 12-crown-4 in dimethylformamide solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650746
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  • 9
    Electronic Resource
    Electronic Resource
    Lithium-7 nuclear magnetic resonance and calorimetric study of lithium crown complexes in various solvents (1980)
    Springer
    Journal of solution chemistry 9 (1980), S. 183-196 
    Details
    ISSN: 1572-8927
    Keywords: Macrocyclic complexes ; crown ethers ; lithium ion ; lithium-7 NMR ; complexation constants ; calorimetry ; enthalpy of complexation ; entropy of complexation ; nonaqueous solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Lithium-7 NMR studies have been carried out on lithium ion complexes with crown ethers 12C4, 15C5, and 18C6 in water and in several nonaqueous solvents. In all cases the exchange between the free and complexed lithium ion was fast on the NMR time scale, and a single, population average, resonance was observed. Both 1:1 and 2:1 (sandwich) complexes were observed between lithium ion and 12C4 in nitromethane solution. The stability of the complexes varied very significantly with the solvent. With the exception of pyridine, the stability varies inversely with the Gutmann donor number of the solvent. In general, the stability order of the complexes was found to be 15C5·Li+〉12C4·Li+〉18C6·Li+. Calorimetric studies on these complexes show that, in most cases, the complexes are both enthalpy and entropy stabilized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648325
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  • 10
    Electronic Resource
    Electronic Resource
    Sodium-23, cesium-133 and thallium-205 NMR study of sodium, cesium and thallium complexes with large crown ethers in nonaqueous solutions (1980)
    Springer
    Journal of solution chemistry 9 (1980), S. 701-714 
    Details
    ISSN: 1572-8927
    Keywords: Crown ethers ; sodium-23 NMR ; cesium-133 NMR ; thallium-205 NMR ; nonaqueous solvents ; enthalpy of complexation ; entropy of complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Formation constants for complexes of dibenzo-21-crown-7, dibenzo-24-crown-8 and dibenzo-27-crown-9 with the Na+, Cs+ and Tl+ ions have been determined by multinuclear NMR measurements in several nonaqueous solvents. The measurements of the cesium complexes were carried out at different temperatures and the enthalpy and entropy of complexation were determined from the temperature dependence of the formation constants. The stabilities of these complexes in solvents of low to medium donicity, —nitromethane, acetonitrile, acetone, methanol, and propylene carbonate, vary in the order Tl+〉Cs+〉Na+. Depending on the relative sizes of the cation and of the ligand cavity, either a three-dimensional ‘wrap-around’ complex or a two-dimensional ‘crown complex’ are formed. For the cesium complexes, the values of ΔH c o and ΔS c o are definitely solvent-dependent and in all cases the complexes are enthalpy stabilized but entropy destabilized. A compensating effect is observed in the variation of the enthalpy and entropy of complexation so that the overall influence of the above solvents on the stability of the complexes is rather limited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645898
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