text: Thioketenes can be stabilized by either steric protection or by electronic effects.  Thus, di-tert-butylthioketene is easily isolated and air-stable. Several examples have been characterized by X-ray crystallography.  The C=S distance is 157 pm and the C=C distance is 124 pm, both bonds being suitable for the C=C=S assignment. The violet color characteristic of thioketenes indicates the small HOMO-LUMO gap.  These compound are prepared by treatment of the acid chloride with phosphorus pentasulfide as described by the following idealized equation:
  Bis(trifluoromethyl)thioketene () is an example of an electronically stabilized thioketene.