Assessment of Experimental Bond Dissociation Energies Using Composite ab Initio Methods and Evaluation of the Performances of Density Functional Methods in the Calculation of Bond Dissociation Energies

Abstract

Composite ab initio CBS-Q and G3 methods were used to calculate the bond dissociation energies (BDEs) of over 200 compounds listed in CRC Handbook of Chemistry and Physics (2002 ed.). It was found that these two methods agree with each other excellently in the calculation of BDEs, and they can predict BDEs within 10 kJ/mol of the experimental values. Using these two methods, it was found that among the examined compounds 161 experimental BDEs are valid because the standard deviation between the experimental and theoretical values for them is only 8.6 kJ/mol. Nevertheless, 40 BDEs listed in the Handbook may be highly inaccurate as the experimental and theoretical values for them differ by over 20 kJ/mol. Furthermore, 11 BDEs listed in the Handbook may be seriously flawed as the experimental and theoretical values for them differ by over 40 kJ/mol. Using the 161 cautiously validated experimental BDEs, we then assessed the performances of the standard density functional (DFT) methods including B3LYP, B3P86, B3PW91, and BH&HLYP in the calculation of BDEs. It was found that the BH&HLYP method performed poorly for the BDE calculations. B3LYP, B3P86, and B3PW91, however, performed reasonably well for the calculation of BDEs with standard deviations of about 12.1-18.0 kJ/mol. Nonetheless, all the DFT methods underestimated the BDEs by 4-17 kJ/mol in average. Sometimes, the underestimation by the DFT methods could be as high as 40-60 kJ/mol. Therefore, the DFT methods were more reliable for relative BDE calculations than for absolute BDE calculations. Finally, it was observed that the basis set effects on the BDEs calculated by the DFT methods were usually small except for the heteroatom-hydrogen BDEs.

Hydrocarbon Bond Dissociation Enthalpies: From Substituted Aromatics to Large Polyaromatics

“…This was also seen by Senosiain et al and from the results given in the paper of Feng et al We can conclude that only composite methods such as CBS-Q and G3 reproduce the BDE of this radical properly whereas DFT methods seriously overestimate the BDE value. [40,38] Our results are in agreement with other data reported in the literature. DiLabio et al and Li et al also suggested that the B3P86 functional was superior to other functionals for the reproduction of BDEs.…”

“…Golden and co-workers further confirmed that the commonly used B3LYP method is insufficient for an accurate evaluation of BDEs and suggested other hybrid methods such as the KMLYP method, that yield rootmean-square (RMS) deviations that are close to the experimental error bars. [38][39][40] Recently a study appeared by Izgorodina, Coote and Radom on trends in RÀX bond dissociation energies in which some new-generation functionals such as B1B95,MPW1PW91, MPW1B95, BB1K, MPW1 K, MPWB1K and BMK were also tested. They found that in particular the BMK functional is very attractive as it shows the smallest systematic errors in the relative BDEs.…”

Diasteromeric Effect on the Homolysis of the C–ON Bond in Alkoxyamines: A DFT Investigation of 1,3-Diphenylbutyl-TEMPO

“…Frequency calculations were performed to confirm that the geometry was a minimum (zero imaginary frequency). The single point energies were then calculated at the B3P86/6-311++G(d,p) level of theory for molecules 1-5 [25]. Radical Stabilization Energies (RSE) of 4 and 5 were calculated at G3B3MP2 (compound method).…”

Conceptual, Qualitative, and Quantitative Theories of 1,3‐Dipolar and Diels–Alder Cycloadditions Used in Synthesis

“…[75] However, does DFT, especially the popular B3LYP, give experimentally accurate kinetic and thermodynamic energies? Recently, many investigations have been devoted to testing the performance of DFT methods for bond dissociation energies, [76] enthalpies of formation, [77] enthalpies of atomization, [78] proton affinities, [79] hydrogen abstraction reactions, [80] radical reactions, [81] weak interactions, [82] S N 2 reactions, [83] pericyclic reactions, [84,85] organic reactions, [86,87] metals, [88] materials, [89] biological applications, and even reactions relevant to astrophysics. [90] This section reviews investigations that give the most reliable quantitative thermochemistries for Diels-Alder and 1,3-dipolar cycloadditions.…”