Solvent-dependent redox thermodynamics of metal amine complexes. Delineation of specific solvation effects

Peter A. Lay, Neale S. McAlpine, Joseph T Hupp, Michael J. Weaver, Alan M. Sargeson

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Solvent-dependent formal potentials, Ef, and reaction entropies, ΔSrc°, for four reversible Co(III/II) couples featuring macrobicyclic "cage" ligands have been obtained. These are utilized, together with corresponding data for other Co(III/II) and Ru(III/II) amine couples and for M(III/II) polypyridine couples, to unravel effects on the redox thermodynamics arising from specific ligand-solvent and other interactions. The solvent dependencies of Ef (vs ferrocenium-ferrocene) for each redox couple are fitted by using a multiparameter approach, incorporating various well-known empirical quantities describing solvent basicity, acidity, polarity, and internal ordering. For most amine couples, solvent basicity appears to play a prevailing role, associated with interactions involving the amine hydrogens, although solvent polarity also exerts a substantial, albeit less solvent-dependent, influence upon Ef. The presence of a deprotonated amide group in the Co(III/II) amine couple is signaled by the additional presence of a significant solvent acidity component in the multiparametric fit. The solvent basicity and other specific contributions to the Ef-solvent behavior for the polypyridine couples are markedly smaller than for the amines. While the inclusion of a "solvent internal ordering" term does not exert a statistically significant influence on the Ef-solvent dependence for any of the redox couples, the ΔSrc°-solvent dependencies are correlated most successfully with this parameter. Besides identifying the major specific solvation factors upon the redox thermodynamics for such inorganic redox couples, the present multiparametric solvent-dependent analysis also provides a novel, although approximate, means by which the extent of such obfuscating influences upon Ef can be assessed.

Original languageEnglish
Pages (from-to)4322-4328
Number of pages7
JournalInorganic Chemistry
Volume29
Issue number21
Publication statusPublished - 1990

Fingerprint

delineation
Solvation
Amines
solvation
amines
Metals
Thermodynamics
thermodynamics
metals
Alkalinity
Oxidation-Reduction
Acidity
acidity
polarity
Ligands
ligands
Amides
amides
Hydrogen

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Lay, P. A., McAlpine, N. S., Hupp, J. T., Weaver, M. J., & Sargeson, A. M. (1990). Solvent-dependent redox thermodynamics of metal amine complexes. Delineation of specific solvation effects. Inorganic Chemistry, 29(21), 4322-4328.

Solvent-dependent redox thermodynamics of metal amine complexes. Delineation of specific solvation effects. / Lay, Peter A.; McAlpine, Neale S.; Hupp, Joseph T; Weaver, Michael J.; Sargeson, Alan M.

In: Inorganic Chemistry, Vol. 29, No. 21, 1990, p. 4322-4328.

Research output: Contribution to journalArticle

Lay, PA, McAlpine, NS, Hupp, JT, Weaver, MJ & Sargeson, AM 1990, 'Solvent-dependent redox thermodynamics of metal amine complexes. Delineation of specific solvation effects', Inorganic Chemistry, vol. 29, no. 21, pp. 4322-4328.
Lay, Peter A. ; McAlpine, Neale S. ; Hupp, Joseph T ; Weaver, Michael J. ; Sargeson, Alan M. / Solvent-dependent redox thermodynamics of metal amine complexes. Delineation of specific solvation effects. In: Inorganic Chemistry. 1990 ; Vol. 29, No. 21. pp. 4322-4328.
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