Se-C Cleavage of Hexane Selenol at Steps on Au(111)
Journal article, 2018

Selenols are considered as an alternative to thiols in self-assembled monolayers, but the Se-C bond is one limiting factor for their usefulness. In this study, we address the stability of the Se-C bond by a combined experimental and theoretical investigation of gas-phase-deposited hexane selenol (CH 3 (CH 2 ) 5 SeH) on Au(111) using photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory (DFT). Experimentally, we find that initial adsorption leaves atomic Se on the surface without any carbon left on the surface, whereas further adsorption generates a saturated selenolate layer. The Se 3d component from atomic Se appears at 0.85 eV lower binding energy than the selenolate-related component. DFT calculations show that the most stable structure of selenols on Au(111) is in the form of RSe-Au-SeR complexes adsorbed on the unreconstructed Au(111) surface. This is similar to thiols on Au(111). Calculated Se 3d core-level shifts between elemental Se and selenolate in this structure nicely reproduce the experimentally recorded shifts. Dissociation of RSeH and subsequent formation of RH are found to proceed with high barriers on defect-free Au(111) terraces, with the highest barrier for scissoring R-Se. However, at steps, these barriers are considerably lower, allowing for Se-C bond breaking and hexane desorption, leaving elemental Se at the surface. Hexane is formed by replacing the Se-C bond with a H-C bond by using the hydrogen liberated from the selenol to selenolate transformation.

Author

Zahra Besharat

Royal Institute of Technology (KTH)

Milad Ghadami Yazdi

Royal Institute of Technology (KTH)

Deborah Wakeham

Royal Institute of Technology (KTH)

M. T. Johnson

Royal Institute of Technology (KTH)

Mark W. Rutland

SP Sveriges Tekniska Forskningsinstitut AB

Royal Institute of Technology (KTH)

M. Gothelid

Royal Institute of Technology (KTH)

Henrik Grönbeck

Chalmers, Physics, Chemical Physics

Langmuir

0743-7463 (ISSN) 1520-5827 (eISSN)

Vol. 34 8 2630-2636

Subject Categories

Inorganic Chemistry

Physical Chemistry

Theoretical Chemistry

DOI

10.1021/acs.langmuir.7b03713

More information

Latest update

9/6/2018 1