Synthesis and comparison of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)butane using DFT study

In this work, we report a combined experimental and theoretical studies on molecular structure, vibrational spectra and NBO analysis of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)butane (BAMTB). The FT-Raman and FT-IR spectra of BAMTB were recorded in the solid phase. The molecular geometry, harmonic vibrational frequencies and bonding features of BAMTB in the ground state have been calculated by using Hartree–Fock (HF) and density functional methods (B3LYP) with standard 6-31G(d,p) as basis set. Stability of the molecule arising from hyperconjugative interactions and charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* antibonding orbitals and E(2) energies confirms the occurrence of intra-molecular charge transfer (ICT) within the molecule. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally, the theoretical FT-IR and FT-Raman spectra of the title molecule have been constructed which shows good agreement with observed spectra.