The adsorption of thiophene on a partially hydrogenated MoS2 cluster. A ZINDO-MRCI study

Two adsorption geometries of thiophene on a Mo5S14 cluster (eta(5) and sigm a) are comparatively analyzed by means of Intermediate Neglect of Different ial Overlap (ZINDO program) calculations, at both the self consistent field and the configuration Interaction (Cl) levels. In order to account for the overestimation of the binding energies (BE) by the NDO methods, the calcul ated raw values for the adsorption system have been corrected to match the experimental (or high level ab initio) BE values for each diatomic bond, co unting the number of bonds on the basis of the analysis of the atomic bond Wiberg index matrix. Calculations show that thiophene adsorbs in a rls coor dination on a partially hydrogenated Mo5S14 cluster. This is the active coo rdination for its cleavage through the C-S bond. Both the sigma and eta(5) coordinations are described as a charge transfer from the adsorbate molecul e to the Mo5S14 cluster, which is more remarkable for the flat adsorption. (C) 1999 Elsevier Science B.V. All rights reserved.