MECHANISM OF THE FORMATION OF (SI-O-)(2)SI-H-H GROUPS IN THE COURSE OF HYDROGENATION OF SILYLENE CENTERS STABILIZED AT THE SILICA SURFACE

Experimental and quantum-chemical data on the mechanisms of processes involving molecular hydrogen and bis-siloxysilylene centers (=Si-O-)(2 )Si:, stabilized at the surface of activated silica (the so-called ''r eactive silica''), are presented. The activation energy of the dehydro genation reaction [GRAPHICS] + H-2 (305 +/- 8 kJ/mol) is estimated fro m the obtained kinetic data, The conclusion on the high activation ene rgy (greater than or equal to 125 kJ/mol) of the reaction of H-2 molec ule addition to bis-siloxysilylene centers is drawn. It is shown that, in the case of reactive silica, the hydrogenation reaction proceeds a s a free radical process initiated by paramagnetic centers, which are stabilized at the surface. The stages of this process are considered.