H2CS

H2CS, commonly known as thioformaldehyde or thiomethanal, is the sulfur analogue of formaldehyde with the chemical formula H2CS. It contains a carbon atom double-bonded to sulfur and two hydrogens attached to carbon, and is typically described as a planar, closed-shell molecule.

In terms of occurrence, H2CS is a reactive, short-lived species that is studied mainly in the gas phase or under cryogenic conditions in laboratory setups. It is produced in situ through photolysis or pyrolysis of sulfur- and carbon-containing precursors and is of interest for understanding sulfur-containing reaction networks. Its stability is limited under many conditions, and it can participate in fast subsequent reactions or polymerization, depending on the environment.

Spectroscopy plays a central role in its study. The rotational spectrum of thioformaldehyde has been measured extensively in the gas phase, enabling its detection by microwave and millimeter-wave astronomy. From these measurements, researchers derive molecular constants and electronic properties such as the dipole moment, which in turn allow astronomers to estimate its abundance and distribution in various environments.

Astrochemically, H2CS has been observed in the interstellar medium, where it contributes to the broader chemistry of sulfur-bearing species. Its detections help constrain models of sulfur chemistry in molecular clouds and star-forming regions, contributing to our understanding of how sulfur is cycled and reservoirs are established in space.

Overall, H2CS serves as a reference molecule for sulfur–carbon chemistry and as a tool for probing chemical processes in both laboratory and astronomical contexts.