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5-Dehydro-m-xylylene

5-Dehydro-m-xylylene

IUPAC name	5-dehydro-1,3-quinodimethane
Other names	5-dehydro-m-xylylene, DMX
Identifiers
CAS number	681440-83-5
Properties
Molecular formula	C₈H₇
Molar mass	103.14 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

5-dehydro-m-xylylene, alternatively known as 5-dehydro-1,3-quinodimethane or DMX, is an aromatic organic triradical and the first known organic molecule to violate Hund's Rule. Its electronic ground state is an "open-shell doublet" rather than a quartet; that is, it contains three low-spin coupled unpaired electrons in three singly occupied molecular orbitals. Because there are radical electrons in both spin states, this compound is said to exhibit antiferromagnetism. Though similar ground states are observed in molecules containing transition metal atoms, it is unprecedented in organic molecules.