Decomposition of Halogenated Molybdenum Sulfide Dianions [Mo₃S₇X₆]^2–(X = Cl, Br, I)

Abstract

Molybdenum sulfides are considered a promising and inexpensive alternative to platinum as a catalyst for the hydrogen evolution reaction. In this study, we perform collision-induced dissociation experiments in the gas phase with the halogenated molybdenum sulfides [Mo3S7Cl6]2–, [Mo3S7Br6]2–, and [Mo3S7I6]2–. We show that the first fragmentation step for all three dianions is charge separation via loss of a halide ion. As a second step, further halogen loss competes with the dissociation of a disulfur molecule, whereas the former becomes energetically more favorable and the latter becomes less favorable from chlorine via bromine to iodine. We show that the leaving S2 group is composed of sulfur atoms from two bridging groups. These decomposition pathways differ drastically from the pure [Mo3S13]2– clusters. The obtained insight into preferred dissociation pathways of molybdenum sulfides illustrate possible reaction pathways during the activation of these substances in a catalytic environment.

Magic cluster sizes of cationic and anionic sodium chloride clusters explained by statistical modeling of the complete phase space

“…The ions are transferred into the ICR cell of the FT-ICR MS, where the cluster size of interest is isolated. Sustained off-resonance irradiation (SORI) 41 collision induced dissociation (CID) experiments are performed [42][43][44] using argon (99.999%) as collision gas at constant pressures between 0.8 Â 10 À8 mbar and 1.0 Â 10 À8 mbar. The parameters for the SORI CID experiment were set to a pulse length of 1.0 s and a frequency offset of 500.0 Hz.…”

Thiomolybdate Clusters: From Homogeneous Catalysis to Heterogenization and Active Sites

“…Gas‐phase fragmentation studies showed that loss of the terminal halides is the energetically most feasible fragmentation route, lending further support to the concept of preferred exchange at the terminal ligand sites. [ 48 ] In a follow‐up work, Ončák and colleagues further linked thermochemical data calculated by DFT to experimental Fourier‐transform ion‐cyclotron resonance mass spectrometry (FT‐ICR MS) and infrared multiple photon dissociation (IRMPD) spectroscopy data measured for a singly protonated [HMo 3 S 13 ] − species. [ 49 ] The authors reported that under their conditions (in the gas phase), only the Mo 3 ‐based species with a singly protonated terminal disulfide ligand is observed.…”