Thermochemically Consistent Free Energies of Hydration for Di- and Trivalent Metal Ions

被引:17
|
作者
Kepp, Kasper P. [1 ]
机构
[1] Tech Univ Denmark, DTU Chem, Bldg 206, DK-2800 Lyngby, Denmark
来源
JOURNAL OF PHYSICAL CHEMISTRY A | 2018年 / 122卷 / 37期
关键词
GIBBS FREE-ENERGY; ELECTRODE-POTENTIALS; SOLVATION; THERMODYNAMICS; WATER; PARAMETERS; DYNAMICS; SOLVENT; CELL;
D O I
10.1021/acs.jpca.8b06674
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
This paper uses the relationship between the standard half reduction potential, the third ionization potential, and the free energies of hydration (Delta G(hyd)) of M2+ and M3+ ions to calculate new values of Delta G(hyd) for M2+ and M3+ ions. The numbers are "thermochemically consistent"; i.e., all numbers agree with the applied thermochemical cycle. This enables the tabulation of many Delta G(hyd) derived mainly from the data compiled by Marcus, but consistent with Delta G(hyd)(H+) = 1100 kJ/mol and SHE = 4.44 V. The accuracy of the new values of Delta G(hyd)(M3+) is by definition similar to the accuracy of the experimental hydration energy of the Delta G(hyd)(M2+) used for calculation, and vice versa, i.e. the new data have the same accuracy or higher than previously reported. As a result, the literature values for Cr3+ and Au3+, and Pd2+ are substantially revised. The approach also allows the calculation of new Delta G(hyd) for metal ions such as Mn3+, Ti2+, Ag3+, Ni3+, Cu3+, and Au2+ and the theoretically interesting but experimentally inaccessible +2 ions of lanthanides. The new numbers enable a discussion of the previously unreported trend in Delta G(hyd)(M3+) for the 3d metal ions, which relates to the ligand field stabilization energies and effective nuclear charge as for the M2+ ions. The new tabulated values should be accurate with the applied assumptions to within 10 kJ/mol and may be of value for other thermochemical calculations, for interpretation of the aqueous trend chemistry of the metal ions, and as benchmarks for theoretical chemistry.
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页码:7464 / 7471
页数:8
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