Establishment of Heterolytic and Homolytic Y−NO2 Bond Dissociation Energy Scales of Nitro-Containing Compounds in Acetonitrile: Chemical Origin of NO2 Release and Capture

Density functional theory for N–NO2 bond dissociation energies of N-nitroacylamide compounds in acetonitrile — Theoretical method assessment and prediction

The performance of various density functional theories (B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, and MPWB95) was examined for calculating N–NO2 bond dissociation energies (BDEs) of 10 N-nitroacylamide compounds. The CBS-4M method was also used. By comparing the calculated results with the experimental values, it was observed that B1LYP/6–31G** and B3LYP/6–31+G** provided accurate BDEs. Especially, B3LYP/6–31+G** was recommended because of its smaller maximum absolute deviation. Further, substituent effects based on the B3LYP/6–31+G** method were analyzed. The result shows that an electron-donating group increases the BDE of the parent C6H5–CON(CH3)NO2, while an electron-withdrawing group decreases the BDE of the parent C6H5–CON(CH3)NO2. Subsequently, the BDEs of the other N-nitroacylamindes were estimated.

Polarized continuum model study of bond dissociation energies of the O–NO2 bond — A density functional theory study and natural bond order analysis

Density functional methods (B3LYP, B3PW91, B3P86, and MPWB95) with 6–31G** basis sets and complete basis methods are employed to investigate the bond dissociation energies (BDEs) of the O–NO2 bond for seven O-nitroalcohol compounds in acetonitrile solution. B3LYP/6–31+G**, (RO)B3LYP/6–311++G(2df,2p), and B3LYP/6–311G(d,p) methods are also used. By comparing the calculated results with the experimental values, B3LYP/6–31+G** is the most accurate method to compute the reliable BDEs for the studied compounds. The substituent effects on the O–NO2 BDEs are analyzed. It is found that electron-withdrawing groups increase the BDE of the parent compound, whereas electron-donating groups decrease the BDE of the parent compound. Further, the natural bond orbital analysis shows that there exist good linear correlations between E(2) and Hammett constants, the BDE, and the difference of the second-order stabilization energies E(2) of lpO3 → BD*(O1–N1) and lpO3 → BD*(O2–N1).

Establishment of the C-NO bond dissociation energy scale in solution and its application in analyzing the trend of NO transfer from C-nitroso compound to thiols

The first set of experimentally determined C-NO bond homolytic and heterolytic dissociation enthalpies in solution is derived by using direct titration calorimetry combined with appropriate electrode potentials through thermodynamic cycles. The homolytic bond dissociation energy scale (BDEs) of the corresponding C-NO bonds in the gas phase was also calculated at the MP2/6-311+G**//B3LYP/6-31G* level and BP86/6-31G*//B3LYP/6-31G* level of theory for the purpose of comparison. The C-NO and S-NO bond thermodynamic parameters were used to predict the trend of NO transfer from C-nitroso substrates to thiols in acetonitrile solution.