Solvent effect on u.-vis and EPR spectra and on the relative stability of mononuelear and binuclear complexes of Cu(II) acetate with pyridine derivatives
✍ Scribed by M. Szpakowska; I. Uruska
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 665 KB
- Volume
- 43
- Category
- Article
- ISSN
- 1386-1425
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✦ Synopsis
Electronic (298.2 K) and ESR (298 and 77 K) spectra have been measured for Cu(O,CMe), solutions in pyridine derivative (L)_solvent (S) binary mixtures (L = pyridine, 3chloropyridine, 2chloropyridine; S = n-hexane, n-heptane, cyclohexane, benzene, chlorobenzene, carbon tetrachloride, propylene carbonate). The results are interpreted in terms of the equilibrium between mononuclear and binuclear complexes: 2Cu(OrCMe), +CU~(O~CMC)~L~ + 2L.
The calculated quotient of the activity coefficients of the two forms strongly depends on the L-ligand activity in the solutions (preferential solvation by L) and on the solvent properties. Chlorobenzene, benzene and carbon tetrachloride compete with pyridine for soivation. The In of the activity coefficient quotient varies linearly with the solubility parameter of the solvent, S, while no satisfactory correlation with the polarity parameter (E -1)/(2& t 1) has been found. The solvent effect on electronic spectra (A,,,,,, E,,,) is stronger for mononuclear, more flexible, complexes than for binuclear ones.