Abstract
Photolysis of Cr(CO)6 in cyclohexane yields solvated pentacarbonyl species within 25 ps. Using high-speed photoacoustic calorimetry, we have determined the heat of reaction for this photofragmentation, directly measuring the energy required to break a single metal–carbonyl bond followed by solvation of the fragments. The energy required to photochemically dissociate a single CO in cyclohexane exceeds the gas phase average bond dissociation energy by at least 11 kcal/mol. However, the determined heat of reaction agrees well with the activation energies derived from thermal decomposition kinetics.