Bonding energies, B3LYP calculations

At B3LYP/TZ(d,p)//B3LYP/TZ(d,p) a- and jr-bond energies were calculated according to the procedure proposed in Reference 56 from Reference 313a. For calculations of H2M=0 at other computational levels, see References 224 and 316. 

Table 10 Calculated a- and 7r-bond energies (kcal mol 1) and bond lengths r (pm) [B3LYP/TZ(d,p)] for the molecules H2C=X and H2Sn=X...

In the calculations of the energy of hydration of metal complexes in the inner coordination sphere, one must consider hydrogen bond formation between the first-shell water molecules and those in bulk water, which leads to chains of hydrogen-bonded water molecules. Such hydrogen-bonded chains of ethanol molecules attached to the central metal ion have been found as a result of DFT B3LYP calculations on ethanol adducts to nickel acetylacetonate, where the calculated energy of hydrogen bonds correlated well with experimental data [90]. 

MNDO or ab initio calculations (Table 5.3). Further confirmation for the preference of 1,2-addition was established by ab initio calculation of the C-H bond energy in hydrogenated fullerenes [35]. Hybrid density functional theory using the B3LYP functional with the 6-31 G(d,p) basis set leads to the bond energies shown in Table 5.3. The most stable bond is found in 1,2 adducts with a bond energy of 2.86 eV, followed by a bond energy of 2.69 eV in 1,4-adducts. All the other addition patterns such as 1,3 addition or addition to a [5,6] bond lead to less stable C-H bonds (Table 5.3). 

TABLE 11. Calculated activation barriers (AE, kcal mol ), H-bonding energies (lin-bonding. kcal moG ) in the peroxy acid and exothermicities (AEreacdon. kcalmol" ) of the epoxidahon reactions of ii-2-butene with substituted peroxy acids at the B3LYP//B3LYP/6-31+G(d,p) level of theory... 

Table 7.3 The C-C bond energy of ethane by HF, MP2(fc), and DFT (B3LYP, M06, and TPSS) calculations, at 0 and 298 K. The basis set is 6-31G. Standard, tabulated bond energies are for dissociation at 298 K. Bond energy = 2(CH3 radical enthalpy) - (CH3CH3 enthalpy). For the radical the unrestricted method (UHF etc.) was used. For the 0 K dissociation enthalpy, the HF and MP2 calculations use energies corrected for ZPE, with the ZPE itself corrected by a factor of 0.9135 (HF) or 0.9670 (MP2) [77]. The 0 K dissociation enthalpy for the DFT calculations is uncorrected for ZPE, and the 298 K dissociation enthalpy is from standard statistical thermodynamics methods [79]. The experimental C-C energy of ethane has been reported as 90.1 0.1 kcal mol-1, i.e. 377 0.4 kJ mol-1 [80]. Calculations are by the author...

The diagonalization reaction of 1,2-thiazetidine A-oxide 10 was theoretically studied at the B3LYP/6-31G level as a concerted bond formation between the diagonal saturated atoms to produce thiirane with the extrusion of HNO (Equation 1). The activation energy was calculated to be 153 kj mol-1, suggesting that the reaction could be observed experimentally <1999TL8893>. 

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