MECHANISM OF REACTIONS BETWEEN SILYLENE GROUPS (SI-O-)(2)SI - IN ELECTRONICALLY EXCITED (TRIPLET AND SINGLET) STATES AND MOLECULAR-HYDROGEN

The mechanism of photochemical hydrogenation of bis(siloxy)silylene ce nters (=Si-O-)(2)Si: (SCs) stabilized at the silica surface is studied . It is shown that the SCs in the electron-excited states abstract a h ydrogen atom from the H-2 molecule: ((=Si-O-)(2)Si:)8+H-2-->(=Si-O-)(2 )Si.-H+H. The rate constants of the corresponding reactions for SCs in the triplet and singlet excited states are determined. In the latter case, the process has virtually no activation barrier The results of t he model quantum-chemical calculations of the transition state for the interaction of the SC in the triplet state with H-2 are presented.