Direct Observation of Thiolate Displacement Reactions on Au(111):  the Role of Physisorbed Disulfides

• Published in: Langmuir Vol. 21; no. 25; pp. 11684 - 11689
• Main Authors: Roper, Mark G, Jones, Robert G
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.12.2005
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Chain length; Saturation; Thiolate; Kinetics; Equilibrium; Displacement; Room temperature
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la050624o

Line-of-sight mass spectroscopy (LOSMS) has been used to study the displacement reaction of (√3×√3)R30° methylthiolate on Au(111) by butylthiolate. The reaction was carried out at room temperature and constant saturation coverage, by exposing the methylthiolate-covered surface to dibutyl disulfide gas. The adsorbed methylthiolate was desorbed as dimethyl disulfide and the cross product methylbutyl disulfide, both identified by LOSMS. This shows that reaction occurs between adsorbed thiolates of different chain length at room temperature, while the kinetics indicate that a rapid equilibrium is established between immobile, chemisorbed thiolates, and highly mobile, physisorbed disulfides.