Arsenic(III)-oxide Intercalates with Potassium Chloride: Water-Induced Varieties and New Synthesis Methods

Synthesis and crystal
structure determination of two new arsenic­(III)-oxide
intercalates with potassium chloride, KCl·As2O3·1/2H2O and KCl·As2O3·3H2O, are reported, and the
crystal structure of the anhydrous KCl·2As2O3 intercalate is redetermined. New ambient-pressure and ambient-temperature
synthesis methods of the compounds are described including a mechanochemical
route. Thermal stability of the compounds has been evaluated, and
KCl·As2O3·3H2O was found
to transform into KCl·As2O3·1/2H2O upon heating at 120 °C. Thermogravimetric
measurements together with infrared and solid-state 1H
nuclear magnetic resonance spectroscopy revealed the presence of water
in KCl·As2O3·1/2H2O. The results of the structural studies on this compound
have led to a proposal for corrections in the crystal structure model
of the NH4Cl·As2O3·1/2H2O intercalate. Last but not least,
interlayer interaction energies in KCl·2As2O3 have been calculated and compared to analogous energies in KN3·2As2O3, which revealed similarities
in the energetic factors stabilizing both compounds.