unhältins
Unhältins are a hypothetical class of chemical compounds that have not been observed or synthesized in reality. The term is a neologism, likely derived from the German word "unhaltig," meaning unsustainable or untenable. In theoretical chemistry, such a designation might be applied to molecular structures that violate fundamental chemical principles or exhibit extreme instability. For instance, an unhältin could be proposed as a molecule with an impossible valency, an anti-Kekulé structure that is inherently unstable, or a configuration that would lead to immediate decomposition or rearrangement.
The concept of unhältins serves as a tool in theoretical and computational chemistry for exploring the boundaries