The adsorption of 1,4-cyclohexadiene (CHD14) on Pt(1 1 1) was analysed using first-principle density functional theoretical calculations. CHD14 adsorbs at the bridge site via quadra-σ-type bonding. The adsorption energy was calculated to be 146 kJ/mol. CHD14 can also adsorb at the hollow site via the formation of a di-σ- and a π-bond with an adsorption energy of 142 kJ/mol. Upon adsorption CHD14 adopts a boat conformation. Strong π-electron donation to the platinum surface in combination with a hyperconjugative interaction of these π-orbitals with the axial σCH orbital helps to explain the observed red shift of the axial C-H stretching frequency and the corresponding C-H bond lengthening.
Bibliographical noteFunding Information:
We would like to thank Venkataram Pallassana for his help in setting up the calculations reported herein. Mark Saeys is grateful to the Fund for Scientific Research-Flanders, Belgium (F.W.O.-Vlaanderen) for a Research Assistantship. This research was carried out in the framework of “InterUniversity Attraction Poles”, funded by the Belgian government and the DWTC office.
- Density functional calculations
- Low index single crystal surfaces
- Models of surface chemical reactions
- Single crystal surfaces
- Vibrations of adsorbed molecules