The structure and possible catalytic sites of MO3S9 as a model of amorphous molybdenum trisulfide: A computational study

The structure and reactivity of Mo3S9 clusters, taken as a model for amorph ous molybdenum trisulfide, have been investigated at the B3LYP density func tional level of theory. Two computed ground-state cluster structures are cl ose in energy and have similar structural parameters and vibrational modes. These values agree well with the available experimental data These cluster structures are considered to be formed simultaneously during the preparati on process of catalysts. Their catalytic activity has been analyzed on the basis of frontier molecular orbital properties (FMO). It is mainly due to 4 d-type orbitals of the unsaturated molybdenum centers without terminal sulf ur coordination. The small HOMO-LUMO gaps suggest that Mo3S9 clusters can a ct as Lewis acids or Lewis bases.