Dissociation energy of the 0-0 bond

On most of the electrocatalysts, oxygen reduction takes place by the formation of high-energy intermediate, peroxide, which is then further reduced to H2O. This is probably a consequence of the high stability of the 0—0 bond, which has a dissociation energy of 494 kj mol. In contrast, the dissociation energy of the 0—0 bond in H2O2 is only 146 kJ mor In order to obtain maximum efficiency and to avoid corrosion of carbon supports and other materials by peroxide, it is desired to achieve a... 

The catalytic activity of Pt towards ORR strongly depends on its O2 adsorption energy, the dissociation energy of the 0-0 bond, and the binding energy of OH on the I t surface. The electronic structure of the IT catalyst (Pt [Pg.114]

It is evident from Table 16.3 that quinones react rapidly with the hydroperoxyl radicals. Calculation shows that the change in the enthalpy of this reaction is relatively small. The dissociation energy of the —H bond in the semiquinone radical 4- 40 is 228.1 kJ mol 1 and the enthalpy of the reaction Q + H02 is A// 220.0 228.1 8.1 kJ mol. ... 

Bond dissociation energies of the C - C bonds in ethane (a a bond only) and ethylene (one a and one k bond) can be used to estimate the strength of the k component of the double bond. If we assume that the 0 bond in ethylene is similar in strength to the 0 bond in ethane (88 kcal/mol), then the k bond is worth 64 kcal/mol. 

From Table 2.4, the average bond dissociation energy of a N=0 bond is 630 kJ mof, which is right in line with the Lewis structure of NO. The bond dissociation energy of each NO bond in NO2 is 469 k J mof, which is about half-way between a N-0 double and an N-0 single bond, suggesting that the resonance picture of NO2 is a reasonable one. 

The properties of mercaptans and alcohols are quite different, although they appear to be similar in nature. The bond dissociation energy of the S-H bond is over 10/kcal/mol lower than the corresponding 0-H bond. The ease of free-radical hydrogen abstraction from a mercaptan supports this fact and permits these compounds to be included in preparative free-radical chemistry. The above fact, along with the different boiling points observed for the mercaptans compared to the corresponding alcohols and the differences in their acidities, helps explain why the chemistry of these two classes of compounds differs in so many ways. 

After geometry optimization, the transition state is found higher (by 3.5 kcal/mol) than the relaxed triplet state. As a consequence, the cleavage process is thermally activated. The dissociation energy of the C-C bond is computed to be 65.5 kcal/mol. Excitation of HAP quantitatively leads to the triplet state from which the dissociation can occur. The very low energy barrier explains the high value of the reported dissociation quantum yield (0.8). All these properties explain the high efficiency of HAP as a photoinitiator. 

Table 3 indicates that the bond dissociation energies of the 0-alkyl (aryl) bond... 

The yttrium monocarbide molecule was only recently observed under high resolution by Simard et al. (37) using Jet-cooled optical spectroscopy. The ground electronic state was determined to be an 0=5/2 state, which was consistent with the ab initio calculations of Shim et al. (38) who predicted a 11 ground state for YC in CASSCF calculations. The experimental work of Simard et al. yielded estimates for both the bond length and harmonic frequency of YC. In addition to their CASSCF calculations. Shim et al. (38) also reported results from mass spectrometric equilibrium experiments, which resulted in a bond dissociation energy of Do = 99.0 3.3 kcal/mol. The results from the present work are shown in Table I. An open-shell coupled cluster singles and doubles... 

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