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.

中文翻译：

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卤化钼硫化物二价阴离子 [Mo3S7X6]2– (X = Cl, Br, I) 的分解

硫化钼被认为是一种有前途且廉价的替代铂作为析氢反应催化剂的替代品。在这项研究中，我们在气相中使用卤化钼硫化物 [Mo ₃ S ₇ Cl ₆ ] ^2–、[Mo ₃ S ₇ Br ₆ ] ^2–和 [Mo ₃ S ₇ I ₆进行碰撞诱导解离实验。 ] ^2–. 我们表明，所有三个二价阴离子的第一个碎裂步骤是通过丢失卤离子进行电荷分离。作为第二步，进一步的卤素损失与二硫分子的解离竞争，而前者在能量上变得更有利，而后者从氯通过溴到碘变得不太有利。我们表明离去的 S ₂基团由来自两个桥接基团的硫原子组成。_{这些分解途径与纯 [Mo 3} S ₁₃ ] ^2-簇有很大不同。对硫化钼优选解离途径的深入了解说明了这些物质在催化环境中活化期间的可能反应途径。