Siloxane bridges as reactive sites on silica gel. Fourier transform infrared–photoacoustic spectroscopic analysis of the chemisorption of diborane

Abstract

The reaction of diborane with the silica gel surface has been studied with Fourier transform infrared photoacoustic spectroscopy (FTIR–PAS). After a dissociative adsorption of diborane on the siloxane bridges, borane reacts with the hydroxyl groups of the silica gel surface, evolving hydrogen gas. Besides this general reaction (a), a new reaction (b) is observed, which is competitive with the direct boranation of the hydroxyl groups. The siloxane bridges act as reactive chemisorption sites, resulting in the formation of silane groups. [graphic omitted]