Absolute bond strengths

A generalized method for determining both relative and absolute bond strengths to an ion center by CID has been developed by Cooks and co-workers. In extensive studies on X - (56) and Ag" " (57), they demonstrated that under appropriate conditions, if AX is more intense than BX in the competitive CID processes 16 and 17, then D (X -A) > D (X -B). This relative bond energy information can be... 

Average uncertainties in absolute bond strength values are on the order of 5 kcal/mol. For experimental errors on specific measurements see the source. 

Hydrofluoro ethers have been proposed as a new generation of CFG alternatives. The absolute rate constants for the abstraction of a hydrogen atom by CF with several hydrofluoro ethers have been examined using VLPR monitored by quadrupole MS. The rate parameters for abstraction were found to correlate well with the theoretical C-H bond strengths determined by ab initio calculations. 

The C-H bond strength is largest for primary C-H bonds at —101 kcal mol-1, decreasing to 98 kcal mol-1 for secondary and 96 kcal mol-1 for tertiary C-H bonds (Lide, 1998-1999). Hence one expects that, all else being equal, a tertiary C-H will react faster than a secondary C-H, which in turn will react faster than a primary C-H. Greiner (1970), whose measurements of the absolute rate constants for OH reactions in the mid-1960s provided the first clue of the potential importance of OH in the troposphere, suggested that... 

As can be seen, the alcohol autocomplexes possess the highest strength the bond strength in the series of amine complexes with alcohol falls from the primary to the tertiary ones, which proves the decisive role of steric factors in the formation of H-complexes with amines. At low temperatures, the equilibrium constant of the A H complexes falls in the series Keql > Keq 2 > Keq3 however, at temperatures over 6Q-70 °C the series becomes reversed. It means that during the reaction at elevated temperatures not only the absolute but also the relative concentrations of the A2H... 

Studies to determine absolute bond enthalpies Z)(Ti-R) in TiRXBu SiNHXsilox (R = alkyl group) from relative bond strength measurements have been performed.243... 

Table 3. Absolute iridium-X bond strengths in Cp Ir(PMe3)X2 complexes...

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