Interaction of -CClx (x=1-3) with Ru2 and RuSn dimers: a density functional study

Density functional calculation were performed on the Ru2 and RuSn metal dimers and the species formed from their interaction with -CClx (x=1-3) fragments. The importance of these fragments in the hydrodechlorination of carbon tetrachloride has been motivated this study aiming to contribute to understand the effect of the tin in the performance of the noble metals based catalysts. We have observed that the carbon tetrachloride does not form a precursor with the metal dimers. The CCl4 readily dissociates forming adsorbed chlorine and -CCl3 complexes. The chlorine atoms prefer to adsorb on the bridge sites and the RuSn-Cl binding energy is about 5 kcal mol−1 larger than the Ru2-Cl binding energy. The Ru2-CClx (x=1-3) binding energies are larger than the respective RuSn-CClx (x=1-3) binding energies. However, the reaction energy of the dechlorination of CCl4 leading to adsorbed -CClx (x=1-3) and chlorine is thermodynamically more favorable for RuSn than the Ru2. The differences between Ru2 and RuSn systems have been discussed based on the different interaction mechanism due to the presence of the tin center and its affinity for the chlorine atoms.