Hydride affinity table

Table S3. Solution Hydride Affinity of Some Carbocations...

The phenyl cation is an extremely unstable cation, as is reflected by the high hydride affinity shown in Table 5.2. In this case, the ring geometry opposes rehybridization so the vacant orbital retains sp character. Because the empty orbital is in the nodal plane of the ring, it receives no stabilization firom the n electrons. 

Table 8.6 shows the hydride affinities calculated for a related series of compounds at... 

Ion cyclotron resonance (ICR) spectroscopy has been used to determine the reaction enthalphy (A//r) of hydride-transfer reaction of silanes with various hydrocarbons having known hydride affinities (Reaction 2.19). The hydride affinities of R3Si+, D//(X3Si+—H ) = Affbase, were obtained from Equation (2.20) and are summarized in Table 2.6 [30,31]-... 

The influence of cyclopropyl on the gas phase stability of carbocations as measured by ion cyclotron resonance is shown in Table 14, along with data for some reference compounds. The results are given as gas phase basicities, GB, and proton affinities, PA, defined as AG° and AH°, respectively, for dissociation of the protonated molecule, as in equation 11. In addition hydride affinities D(BH H ) for some cations defined as — AH° for equation 18 are included. For the gas phase basicities and proton affinities the products B are alkenes, amines, nitriles or carbonyl compounds, and thus for these values the stability of the cation is compared to a derivative where the substituent is conjugated with a carbon-carbon or carbon-oxygen double bond, or a nitrogen lone pair, whereas for hydride affinities the products are saturated. 

TABLE 14. Gas phase basicities, proton affinities and hydride affinities for cations... 

Several criteria, including hydride affinities of carbocations (R+—H heterolytic BDE) and adiabatic ionization potentials of the corresponding free radicals (Table 1.30), indicate the order of decreasing stability of fluoromethyl carbocations to be CHF2+ > CH2F+ > CF3+ > CH3+ (Scheme 1.54) [1],... 

Table 3.10 gives values for the hydride affinity for some carbocations. There is good agreement with the theoretical results shown in Figure 3.18 and the data in Table 3.10. 

Table 3.25. Substituent Effects on Hydride Affinity of XYC=0 by an Isodesmic Reaction Sequence (in kcal/mol by G2(MP2) Calculations) ...

Table 20. The B3LYP/6-31+G(d) computed hydride affinities (eV) for some carbocations...

Table 21. Hydride affinities (eV) computed by Quadratic Complete Basis Set...

Table 2 lists selected carbenium ions in order of increasing stability, along with their hydride affinity and the solvolysis rate constants of the corresponding alkyl halides. 

Table 8.6 shows the hydride affinities calculated for a related series of compounds at the G2 level of theory. The computation was made on the basis of two isodesmic reactions that allow a comparison of the hydride affinity of the compound with that of formaldehyde. These results place the C=0 stabilizing effect in the order... 

TABLE 7.5 Examples of Proton Affinities (kJ/mol), Hydride Affinities (kJ/mol), and Recombination Energies (eV) ... 

Secondary alkyl selenides are reduced by (TMS)3SiH, as expected in view of the affinity of silyl radicals for selenium-containing substrates (Table 4.3) [40]. Reaction (4.23) shows the phenylseleno group removal from the 2 position of nucleoside [50]. Similarly to 1,3-dithiolanes and 1,3-dithianes, five- and six-membered cyclic selenoacetals can be monoreduced to the corresponding selenides in the presence of (TMS)3SiH [51]. The silicon hydride preferentially approached from the less hindered equatorial position to give transicis ratios of 30/70 and 25/75 for the five-membered (Reaction 4.24) and six-membered cyclic selenoacetals, respectively. 

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