thioformaldehyde
{{Chembox
| ImageFileL1 = Thioformaldehyde-2D.png
| ImageSizeL1 =
| ImageAltL1 = Structural formula of thioformaldehyde
| ImageFileR1 = Thioformaldehyde-3D-vdW.png
| ImageSizeR1 =
| ImageAltR1 = Ball-and-stick model of the thioformaldehyde molecule
| IUPACName = Thioformaldehyde
| OtherNames =
| SystematicName = Methanethial
| Section1 = {{Chembox Identifiers
| CASNo = 865-36-1
| EINECS = 200-454-1
| PubChem = 79115
| ChemSpiderID = 71446
| SMILES = C=S
| StdInChI = 1S/CH2S/c1-2/h1H2
| StdInChIKey = DBTDEFJAFBUGPP-UHFFFAOYSA-N }}
| Section2 = {{Chembox Properties
| Formula = CH2S
| MolarMass = 46.09
| Appearance = unknown
| Density =
| MeltingPt =
| BoilingPt =
| Solubility = }}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
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}}
Thioformaldehyde is the organosulfur compound with the formula CH2S. It is the simplest thioaldehyde. This compound is not observed in the condensed state (solid or liquid) because it oligomerizes to 1,3,5-trithiane, which is a stable colorless compound with the same empirical formula.
Despite the instability of these concentrated forms, thioformaldehyde as a dilute gas has been extensively studied. For these purposes, it is produced by thermal decomposition of dimethyl disulfide.{{cite journal |doi=10.1016/0022-2852(71)90284-0 |title=Microwave spectrum, ground state structure, and dipole moment of thioformaldehyde |date=1971 |last1=Johnson |first1=Donald R. |last2=Powell |first2=Francis X. |last3=Kirchhoff |first3=William H. |journal=Journal of Molecular Spectroscopy |volume=39 |pages=136–145 |bibcode=1971JMoSp..39..136J }} The molecule has been observed in the interstellar mediumDespois, D., "Radio Line Observations of Molecular and Isotopic Species in Comet C/1995 O1 (Hale-Bopp) Implications on the Interstellar Origin of Cometary Ices", Earth, Moon, Planets 1999, 79, 103-124. and has attracted much attention for its fundamental nature.{{cite journal|doi=10.1146/annurev.pc.34.100183.000335|title=The Spectroscopy of Formaldehyde and Thioformaldehyde|year=1983|last1=Clouthier|first1=D. J.|last2=Ramsay|first2=D. A.|journal=Annual Review of Physical Chemistry|volume=34|pages=31–58|bibcode=1983ARPC...34...31C}} The tendency of thioformaldehyde to form chains and rings is a manifestation of the double bond rule.
Although thioformaldehyde tends to oligomerize, many metal complexes are known. One example is Os(SCH2)(CO)2(PPh3)2.{{cite journal |doi=10.1039/C0DT00975J|title=The coordination chemistry of small sulfur-containing molecules: A personal perspective|year=2011|last1=Schenk|first1=Wolfdieter A.|journal=Dalton Trans|volume=40|issue=6|pages=1209–1219|pmid=21088787}}
