Structure of copper complexes adsorbed on a silica gel surface chemically modified with benzimidazole

Abstract

Silica gel having a particle size between 0.2 and 0.05 mm and a specific surface area, S_BET= 473 m² g^–1, was chemically modified with benzimidazole. Adsorption isotherms of CuX₂(X = Cl, Br or ClO₄) from ethanol and acetone solutions were studied at 298 K. The metal is bonded to the surface through the free nitrogen atom of the attached benzimidazole. The average number of ligands co-ordinated to the central metal ion was shown to depend on the solid surface loading by the solute. At low loading the electronic and ESR spectral parameters indicated that the copper ion is in a distorted-tetragonal symmetry field.