- Structural study of the complex of Al (III) with 1,2-benzenediol. Solvent effects

M. I. SANCHO; A.H.JUBERT; S. E. BLANCO; , F. H. FERRETTI; E.A.CASTRO

Global Journal of Molecular Sciences

IDOSI Publications

Año: 2006 vol. 1 p. 1 - 41

1990-9241

The stability of the complex formed by two molecules of 1,2-dihydrobenzene and one molecule of AlCl3 in solution with different permitivity and temperatures was investigated by means of the B3LYP/6-31G(d) method and using the IPCM model. It was assumed that the formation of the complex takes place by simple reactions between ions of opposite charges. It was also proposed an equation that explains the changes of the complexation equilibrium constant with the permitivity of the reaction medium. The calculations performed allowed to prove that the increase of the hydrogen-bon donor ability of the solvents favor a higher thermodynamic stability of the reactants with respect to the complex and therefore a decrease of the corresponding equilibrium constants. The non-phase structure proposed for the complex is coherent with the small batochromic shift experimentally observed. In the complex molecule the planes containing the phenyl rings are inclined by 9,2 withrespect to the plane that includes the aluminium nd oxygen atoms. It was concluded that the formation of the complex is an endothermic process which involves covalent bonds between metal atom and oxygen atoms of catechol and stronger coulombic attractions between the referred atoms and water molecules.