Stereochimica di alcuni acquo-complessi assorbiti su bentonite

The stereochemistry of some hydrated ions on the interlamellar surfaces
of bentonite has been investigated by spectroscopic methods.
The coordination of adsorbed ions estimated on the basis of d001values
has been confirmed by diffuse reflectance and ESR spectra.
When the d001value is ~ 12.4 Å a monolayer of water occupies the
« interlayer »; the ion is coordinated to four water molecules in the xy plane
and to two silicate oxygens along the z axis.
When the d001value is 14-3 Å two layers of water occupy the «interlayer
»; the ion is octahedrally coordinated to six water molecules and the
symmetry axis of the acqueous-complex is inc1ined with respect to the sili·
cate layers at an angle of 45º
When the d001value is ~15.0 Å, three layers of water are present in
the interlayer; the ion is octahedrally coordinated to six water molecules
but the symmetry axis is perpendicular to the silicate layers.