Abstract:
Density functional calculations of the adsorption of ethynylbenzene on the Au(111) surface show that, after
cleavage of the C-H bond, the terminal carbon makes a strong covalent bond to the surface. The bond
energy is shown to be about 70 kcalâmol-1 with the fcc hollow site being most stable and the molecule
oriented perpendicular to the surface. Adsorption without elimination of hydrogen is also possible via a hydrogen
1,2 shift to form a vinylidene surface-bound species, or opening of the C-C triple bond and adsorption
through the two carbon atoms in a flat conformation. The reaction energy for formation of the surface-bound
vinylidene is estimated to be 5 kcalâmol-1 exothermic relative to the isolated ethynylbenzene and gold substrate.
