Conformational analysis, vibrations and chemical shifts calculation of benzenesulfonicacid hydrazide by DFT methods

Conformation analysis of benzenesulfonic acid hydrazide have been carried out in gas phase by DFT B3LYP/6-311G(d,p) and MP2/6-311G(d,p) method, total six enantiomer pairs have been obtained. The aqueous solvation of this molecule have been studied at the DFT B3LYP/6-311G(d,p) and MP2/6-311G(d,p) level using C-PCM (Coductor like- Polarizable Continuum Model) and three enantiomer pairs have been obtained. C-PCM results show that stability of conformers were affected, some conformation becoming unstable in the aqueous phase and energy ordering of the conformers is also different. Several transition structure were identified for gas phase with DFT B3LYP/6-311G(d,p) and B3LYP/6-311G(d,p)/C-PCM level in aqueous medium. Magnetic isotropic shielding tensors have been calculated gas phase GIAO B3LYP/6-311++G(2d,2p) level and in aqueous medium by B3LYP/6-311++G(2d,2p)/C-PCM and 6-311G++G(2df,2pd)/C-PCM methods and correlated with the experimental chemical shifts. IR frequency and intensity are also calculated by DFT B3LYP/6-311G(d,p) level for gas phase and B3LYP/6-311++G(2d,2p)/C-PCM and B3LYP/6- 311G++G(2df,2pd)/C-PCM levels in aqueous medium and compared with corresponding experimental result.