Dynamics of the thermal dissociation of unsaturated cyclic ketones: Nascent vibrational energy distributions in the products

Article abstract of DOI:10.1021/ja00169a015

It has been found that in thermal dissociation of both norbornenone and 3-cyclopentenone the CO is formed with less than half its statistical share of the energy released from the transition state. We have used (VV) coupling between the products, 1,3-cyclohexadiene and butadiene, respectively, to probe their nascent vibrational energy. They are both born vibrationally excited. It seems that much of the energy released appears as vibrational energy of these molecules. In the transition state the CO group must have a bond length close to that of the free molecule. These results do not permit a decision between symmetric and asymmetric bond cleavage. However, separate experiments in which the rotational distribution has been measured establish that the dissociation does not occur by symmetric bond rupture.