The Formation of MgS & MgO Monomers and Dimers from Magnesium, Oxygen, and Sulfur Hydrides

The reaction of SH + MgH is shown in this quantum chemical study to be an energetically downhill pathway leading to the astronomically known MgS molecule as well as H₂. Hence, the formation of MgS in the gas phase is now shown to be a possible contributor to this diatomic molecule's observed astronomical abundance. Similarly, MgO can form through a related process with OH + MgH, but the energy costs are higher, implying that MgH could be consumed in reactions with SH faster than those with OH. Hence, MgS may be more abundant than MgO as a result in line with current astronomical observations. Additionally, further additions of MgS/MgO can lead to the dimers of these molecules, indicating that the formation of nanoclusters is possible. These structures could be the building blocks for larger dust grains and mineral-based materials that populate protoplanetary disks and, ultimately, lead to rocky bodies.