Heat of formation predictions of various nitro-substituted azoles by G4MP2-SFM scheme

Heats of formation (Delta H-f) of various nitro-substituted azoles were predicted by Gaussian-4 MP2 combining with systematic fragmentation method (SFM), G4MP2-SFM. The overall mean absolute deviations and root-mean-square deviations of the particular opt-G4SFM(1,2) scheme are 2.0 and 2.6 kcal/mol, respectively, on the predictions of 48 molecules. Overall, each additional nitrogen in the azole ring increases Delta H-f by 10-30 kcal/mol. While the effect of the NO2 substitution to carbon (NO2(C)) is minor, that to nitrogen (NO2(N)) increases Delta H-f by 15-32 kcal/mol. In addition, we found that second-neighbor contribution is also significant for nonbonding interactions between NO2 groups, which increase Delta H-f by 3-4 kcal/mol.