The mechanism of adsorption of sulfides on gold(111).

Abstract

In this thesis, we present the electrochemical and spectroscopic characterization of the monolayer on a Au(111) single crystal formed by alkanethiols, dialkyldisulfides and dialkylsulfides. We found that all these organic sulfur compounds adsorb dissociatively and form a monolayer of thiolates. We also study the monolayer formed by a cyclic sulfide, pentamethylene sulfide. We found that this sulfide forms a monolayer of an aldehyde terminated thiolate. We suggest that the sulfide is oxidatively dissociated by molecular oxygen and adsorb on the gold surface. A mechanism of this process is also described. We use S$\sb{\rm N}$2 chemistry to examine the reactivity of this cyclic sulfide. The fact that an S$\sb{\rm N}$2 reaction occurs on the gold surface proves the formation of a reactive chemisorbed sulfide on the gold surface.