INFRARED STUDY OF THE CHEMISORPTION OF PENTAMETHYLANTIMONY ON SILICA

Infrared spectroscopy has been used to study the chemisorption of pent amethylantimony, SbMe(5), on silica. For temperatures of activation fr om room temperature to 1000 degrees C, a single chemisorbed product is formed, =SiOSbMe(4). The hydrogen-bonded silanols react to completion faster than the isolated silanols. Unlike other reactive metal-alkyl compounds, there was no evidence for a significant reaction with silox ane sites, The chemisorbed species do not react with water vapor at ro om temperature or at 100 degrees C. However, upon heating under vacuum to 250-300 degrees C it decomposes to yield surface SiOMe groups and gaseous SbMe(3). Finally, the silanol groups can be regenerated when s urfaces SiOSbMe(4) reacts with gaseous HCl to yield SbMe(4)Cl, the rea ction being SiOSbMe(4) + HCl --> SbMe(4)Cl + SiOH.