Particularities of interaction of electron-donating molecules with a surface of crystalline oxides α-АL2О3, СR2О3 И АL/СR2О3. Model quantum chemical calculations

Within the framework of model of a molecular cluster with the closure of uncompensated valences by hydrogen atoms and semiempirical calculated scheme MNDO-PM/3 in valence base with insert of 3d-orbitals of cromium atoms the electronic energetic and IR-spectroscopic characteristics of surface centers of crystals α-Αl,Ο3, Cr2O3 and Al/Cr,O3 with the incompletely coordinated atoms AT* and Cr* and chemadsorption complexes of NH3, H2O, CH3OH molecules with these centers are calculated. The energetic barriers corresponding to transition between the nondissociative and dissociative adsorption forms are obtained. The electronic and geometric characteristics of the relevant transition states, regularities in changes of adsorption heat, process of surface dissociation (proton transition from one center on another) and characteristic vibration frequencies in investigated series are discussed.