1,2-Difluoroethylene

1,2-Difluoroethylene, also known as 1,2-difluoroethene, is an organofluoride with the molecular formula CHF. It can exist as either of two geometric isomers, cis-1,2-difluoroethylene or trans-1,2-difluoroethylene.
It is regarded as a hazardous chemical for being toxic by inhalation, and a volatile chemical, and it causes irritation when it comes into contact with the skin and mucous membranes.

''E-Z'' relative stability

For most 1,2-disubstituted compounds that exhibit cis–''trans isomerism, the trans isomer is more stable than the cis isomer. However, 1,2-difluoroethylene has the opposite situation, with the cis more stable than the trans'' by 0.9 kcal/mol.