Singlet diradicals: from transition states to crystalline compounds.


Singlet diradicals are usually not energy minima. As observed by femtosecond spectroscopy, they readily couple to form final sigma bonds. Substituent effects allow lifetimes to increase into the microsecond range. Taking advantage of the properties of hetero-elements, a diradical has been prepared that is indefinitely stable at room temperature. The… (More)