Gas-Phase Reactivity Studies of Small Molybdenum Cluster Ions with Dimethyl Disulfide.

Molybdenum sulfide is a potent hydrogen evolution catalyst, and is discussed as a replacement of platinum in large-scale electrochemical hydrogen production. To learn more about the elementary steps of MoS production by sputtering in the presence of dimethyl disulfide (DMDS), the reactions of Mo , x = 1-3, with DMDS are studied by Fourier transform ion cyclotron resonance mass spectrometry and density functional theory calculations. A rich variety of products composed of molybdenum, sulfur, carbon and hydrogen was observed. MoS species are formed in the first reaction step, together with products containing carbon and hydrogen. The calculations indicate that the strong Mo-S bonds are formed preferentially, followed by Mo-C bonds. Hydrogen is exclusively bound to carbon atoms, i.e. no insertion of a molybdenum atom into a C-H bond is observed. The reactions are efficient and highly exothermic, explaining the rich chemistry observed in the experiment.