Ruthenium, bond dissociation energies

The bond dissociation energy of fluoromethane is 115 kcal mol , which is much higher than the other halides (C-Cl, C-Br and C-1, respectively 84, 72 and 58 kcal mol ) [6], Due to its strength, the carbon-fluorine (C-F) bond is one of the most challenging bonds to activate [7], A variety of C-F bond activation reactions have been carried out with different organometallic complexes [8], Among them, nickel [9] and ruthenium complexes have proven to proceed selectively under mild conditions [10],... 

An attempt has been made to calculate the metal-ring bond dissociation energy in ferrocene, and in the bisoyclopentadienyl compounds of nickel, ruthenium and osmium, for which heat of formation data are available. Some of these heats of formation are shown in Table 5. 

Figure 7.22 Phosphine bond dissociation energies at OK (i.e., including zero-point vibrational energies) for the first- and second-generation ruthenium-based Grubbs catalysts, as calculated and obtained in ESI-MS experiments. (Adapted from Ref. [85]).

These trends are consistent with observations made to characterize the chain growth of surface carbon that was deposited by methane decomposition. In a row of the periodic table, the selectivity to hydrocarbon formation was foimd to increase from right to left for example, palladium shows a lower selectivity than ruthenium 111,112). Metals such as platinum and iridium are characterized by higher selectivities for chain growth initiated from "Cl" species than other metals because of their relatively high M—C bond energies. However, platinum and iridium are unsuitable as Fischer-Tropsch catalysts because the dissociation of CO is too slow. 

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