Methidathion complexes with homoionic and surfactant-modified montmorillonites.

The formation of the insecticide methidathion (S-[(5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)methyl] O,O-dimethyl phosphorodithioate) complexes with inorganic cation-saturated (Mg2+, Ca2+, Cu2+, and Ni2+) montmorillonites was investigated. The nature and structure of the complexes was determined by X-ray diffraction and infrared spectroscopy. The arrangement of the pesticide molecule in the interlayer space was also considered from ab initio calculations using simpler related molecules.

Adsorption Mechanism and Structure of the Montmorillonite Complexes with (CH(3))(2)XO (X=C, and S), (CH(3)O)(3)PO, and CH(3)-CN Molecules.

The formation of complexes with different ligands in the interlayer space of montmorillonite saturated in Na(+), Mg(2+), Ca(2+), Co(2+), Cu(2+), Ni(2+), Fe(3+), and Cr(3+) was studied. Acetone, acetonitrile, dimethyl sulfoxide, and trimethylphosphate were used as ligands. The nature of the complexes was studied by means of X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, microcalorimetry, and ab initio quantum mechanical methods.

Adsorption of Water Vapor by Homoionic Montmorillonites. Heats of Adsorption and Desorption.

Adsorption isotherms for water vapor, basal spacing, and immersion heats and water desorption heats of Li+, Na+, Mg2+, Ca2+, Cu2+, and Fe3+ montmorillonite are measured at various relative humidities (r.h.).