Cis–trans conversion of the CH3S–Au–SCH3 complex on Au(111)
The RS–Au–SR complex (RS– being an alkylthiolate group) has been determined to be an important structural motif at the interface of self-assembled monolayers (SAMs) of thiolate on gold. We investigate the conversion between two stable configurations (cis and trans) of the CH3S–Au–SCH3 complex on Au(111) by applying density functional theory. We show that this cis–trans conversion has a barrier of only 0.5 eV, indicating that the two geometrical isomers can easily interchange on Au(111) to facilitate packing of the CH3S–Au–SCH3 complexes on Au(111). We further examine how this conversion connects two stable structural models recently predicted for the well known c(4 × 2) superstructure of SAMs on Au(111).