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
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

5-Dehydro-m-xylylene (DMX) is an aromatic organic triradical and the first known organic molecule to violate Hund's Rule.^[1]

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. The 5-dehydro-m-xylylene anion (DMX^-) has also been studied extensively. It has a triplet ground state consisting of a phenyl anion and a m-xylylene biradical.

References

1. ^ L Slipchenko et al. (2004). "5-Dehydro-1,3-quinodimethane: A Hydrocarbon with an Open-Shell Doublet Ground State". Angewandte Chemie International Edition 43 (6): 742. doi:10.1002/anie.200352990. PMID 14755709. 

External links

• Physics web - Radical molecule breaks the rules
• Purdue University Department of Chemistry - ‘Rule-breaking’ molecule