Knowledge Bank

Photodissociation spectra obtained for several $C6H8\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$. radical cations, using a pulsed ion cyclotron resonance technique, have been analyzed for structural Information. The current study, which includes the isomeric cyclohexadiene and methyl-cyclopentadiene radical cations, extends che work done previously on the cation radical of 1,3,5 $hexatriene1$ The correlation of peak positions and cross-sections in the spectra of the cyclohexadiene is outers suggests o thermal conversion of 1,4 cyclohexadiene to the conjugated isomer. The possibility of the thermal ring-opening of 1,3 cyclohexadiene radical cation has also been studied, but is ruled out by the spectrum, consistent with orbital symmetry considerations. The comparison of spectra and electronic transitions includes those observed by other methods, such as photoelectron-spectroscopy.