Doi:10.1016/0040-4020(95)00335-6

Ab initio study of the effect of N-substituents on the properties of pyrazoles

A series of fourteen derivatives of pyrazole have been calculated at the MP2-6-31G^∗∗ level. 1. N-H; 2. N-BH₂;3. N-BH₃⁻; 4. N-CH₃; 5. N-CHO; 6. N-CF₃; 7. N-NH₂; 8. N-NO₂; 9. N-OH; 10. N-AlH₂; 11. N-SiH₃; 13. N-SO₂H; 14. N-oxide. The first thirteen are derivatives of the parent pyrazole nitrogen N(1) and the last one is pyrazole N-oxide. The substituents have been selected to cover a wide range of electronic effects. The theoretical results are discussed in relation with geometries, energies, vibrational spectra, Bader analysis and tautomerism (in the case 1-hydroxypyrazole/pyrazole N-oxide).