Adsorption of thiophene on transition metal atoms (Co, Ni and Mo) modified Al20O30 clusters: DFT approaches

► The impurity of transition metal promotes the activity of catalyst by an elongation of CS bond. ► There are π-backdonation exists in the η2 and η5 bonding modes. ► The ν(CC)sym bands are shifted to lower wavenumbers in the η5 bonding modes.