Home – Home – Jornals – Journal of Structural Chemistry 2017 number 2

Conformational properties of a benzenesulfonic acid hydrazide molecule and its para -nitro and para -methyl derivatives, which have found wide application as porofors and biologically active compounds, are studied. It is found that the benzenesulfonic acid hydrazide molecule has six conformers with relative energies of 0//0 kcal/mol, 0.34//0.98 kcal/mol, 2.51//2.25 kcal/mol, 2.54//2.56 kcal/mol, 2.90//3.28 kcal/mol, 6.64//6.43 kcal/mol (MP2//DFT(B3LYP) with the cc-pVTZ basis set), each conformer has an enantiomer. Conformers differ from each other in the relative orientation of fragments of the -SO₂NHNH₂ group, energies of frontier orbitals, the direction and value of dipole moments. It is shown that the introduction of a nitro or methyl group into the para -position practically does not affect the conformational properties of the sulfonyl hydrazide group. A change in the structure of benzenesulfonic acid hydrazide in the crystal-gas transition is considered and it is revealed that in the crystal the conformation similar in structure to one of the high-energy conformers of the free molecule is stabilized. The NBO analysis of the electron density distribution is performed and it is shown that the occurrence of the gauche effect in all conformers of the molecules under study can be interpreted by the manifestation of the total action of strong anomeric effects between the lone pairs of nitrogen atoms and antibonding orbitals of S=O, N-H, C-S, and N-S bonds.