Abstract Due to its strong electrophilic character sulfur trioxide can be inserted in bonds between carbon and the elements silicium, germanium, tin and lead. This reaction takes place under very mild conditions and in general yields organometallic derivatives of sulfonic acids, R 3 M OSO 2 R (M= Si, Ge, Sn and Pb; R= alkyl or aryl). Under suitable conditions organometal sulfates and sulfonic acid anhydrides,(R 3 MO) 2 SO 2 and RSO 2 OSO 2 R, ...