Chlorine peroxide ($\mathrm{ClOOCl}$)

The peroxy-linked chlorine oxide $\mathrm{ClOOCl}$, often written $\mathrm{C}{\mathrm{l}}_2{\mathrm{O}}_2$ in a chlorine monoxide dimer cycle. Thermal return to two chlorine monoxide radicals competes with a photolytic pathway that ultimately yields two chlorine atoms. The formula alone should not be taken as specifying every possible dichlorine-dioxide isomer.