Matrix isolation studies of the reactions of silicon atoms. I. Interaction with water: The infrared spectrum of hydroxysilylene HSiOH

Abstract

This study focuses on the interactions and reactions of silicon atoms and molecules with water. Initially, a silicon–water adduct ( Si:OH 2 ) is formed, as noticed from the red shift of the ν 2 bending modes of H 2 O , HDO, and D 2 O . This silicon “hydrate’’ complex rearranges spontaneously through hydrogen tunneling to give HSiOH and HSiOD as final products of the reaction of Si with H 2 O and HDO. Photolysis of Si:OD 2 with λ⩾400 nm is necessary for the production of the deuterated insertion product DSiOD. All silicon hydroxy–hydrides undergo a photolytic decomposition reaction when strongly irradiated to give silicon monoxide and molecular hydrogen or two hydrogen atoms. Band assignments for trans‐HSiOH, trans‐ and cis‐HSiOD, and DSiOD have been made. It appears that the cis‐isomer converts to the more stable trans‐isomer when the matrix is heated. The SiOH bond angle has been calculated for a planar structure of C s symmetry using the Redlich–Teller product rule and the torsional frequencies for HSiOH, HSiOD, and DSiOD. Normal coordinate analyses have been carried out using the measured frequencies for six isotopomers, namely, HSiOH, HSiOD, DSiOD, HSi 18 OH , HSi 18 OD , and DSi 18 OD . Thermodynamic properties have also been calculated for this new species.