INVESTIGADORES
SANCHO Matias Israel
artículos
Título:
Complexation of Zn(II) by catechol in hydroxylic solvents
Autor/es:
SANCHO, M.I; BLANCO, S. E.; FERRETTI, F.H.; JUBERT, A.H.; CASTRO, E.A.
Revista:
Journal of the Argentine Chemical Society
Editorial:
Asociación Química Argentina
Referencias:
Lugar: Buenos Aires (Argentina); Año: 2006 vol. 94 p. 143 - 155
ISSN:
0365-0375
Resumen:
The stability of the complex formed by one molecule of 1,2-dihydroxybenzene and
one molecule of zinc acetate in solutions with different permittivity and temperature was
investigated by means of spectroscopic and chromatographic methods. The Becke hybrid
three-parameter nonlocal exchange functional combined with the Lee-Yang-Parr dynamic
correlation functional method (B3LYP/6-31G(d)) and the isodensity polarized continuum
model (IPCM) were used in the calculations. It was assumed that the formation of the
complex takes place by a reaction between ions of opposite charges. It was also proposed
an equation to explain the changes of the constant of the complexation equilibrium with the
permittivity of the reaction medium. The calculations allowed us to prove that the increase
of the hydrogen-bond donor ability of the solvents favours a higher thermodynamic stability
of the reactants with respect to the complex and, as a result, a decrease of the corresponding
equilibrium constants. The non-planar structure proposed for the complex is consistent
with the experimentally observed hyperchromic shift. The plane, in the complex molecule,
containing the aromatic ring is tilted by approximately 18º with respect to that of the zinc
and oxygen atoms. It was concluded that the formation of the complex is an endothermic process.