NNO2 bond dissociation energies in acetonitrile: An assessment of contemporary computational methods

• BMK and B3P86 methods reproduce better BDEs.
• Electron donating group increases the BDE, electron withdrawing group decreases the BDE of the parent compound.
• There exists good correlation between E(2)of lpN1 → BD*(O1N2) and Hammett constant.
• There exists good linear correlation between BDE and E(2) of lpN1 → BD*(O1N2).

The assessment of the NNO2 bond dissociation energies (BDEs) was performed by various calculating methods (B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, CBS-4M and M06-2X) at 6-311+G(2d,p) basis set. Compared with the experimental BDEs, the results show that BMK and B3P86 methods reproduce the experimental values well. The mean absolute deviations from the experimental values obtained by BMK and B3P86 methods were 0.5 and 1.5 kcal/mol, respectively. B3LYP, B3PW91, B1LYP, MPWB1K and PBE0 methods underestimated the homolytic NNO2 BDEs. B3LYP, B3PW91, B1LYP, M06-2X, CBS-4M methods failed to provide an accurate description of NNO2 BDEs for N-Nitrosulfonamide compounds and showed larger mean absolute deviations and maximum deviations. Further, substituent effect based on BMK/6-311+G(2d,p) method was analysis. Natural bond orbital analysis shows that there exist good linear correlations between E(2) of lpN1 → BD*(O1N2) and Hammett constants and a better correlation between the BDEs and the second order stabilization energy E(2) of lpN1 → BD*(O1N2).

The assessment of the NNO2 bond dissociation energies was performed by using B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, CBS-4M and M06-2X methods at 6-311+G(2d,p) basis set. The results show that BMK and B3P86 methods reproduce the experimental values well. B3LYP, B3PW91, B1LYP, MPWB1K and PBE0 methods underestimate the homolytic NNO2 BDEs. Further, substituent effect based on BMK/6-311+G(2d,p) method is analysis. Natural bond orbital analysis shows that there exist good linear correlations between E(2) and Hammett constants, the BDE and E(2) of lpN1 → BD*(O1N2).Figure optionsDownload high-quality image (82 K)Download as PowerPoint slide