Structural and spectroscopic analysis of 3-[(4-phenylpiperazin-1-yl)methyl]-5-(thiophen-2-yl)-2,3-dihydro-1,3,4-oxadiazole-2-thione with experimental (FT-IR, Laser-Raman) techniques and ab initio calculations

• The FT-IR and Laser-Raman spectra of the title compound were recorded in solid phase.
• The optimized geometry and vibrational frequencies were calculated for the first time.
• The HOMO–LUMO energies and related molecular properties were evaluated.

Experimental and theoretical harmonic vibrational frequencies of 3-[(4-phenylpiperazin-1-yl)methyl]-5-(thiophen-2-yl)-2,3-dihydro-1,3,4-oxadiazole-2-thione have been investigated in this paper. Experimental FT-IR (400–4000 cm−1) and Laser-Raman spectra (100–4000 cm−1) of title compound in solid phase have been recorded. Theoretical vibrational frequencies and geometric parameters (bond lengths and bond angles) have been also calculated using ab initio Hartree Fock (HF), density functional theory (B3LYP hybrid functional) methods with 6-311++G(d,p) basis set, for the first time. Assignments of vibrational frequencies have been performed by potential energy distribution (PED) analysis. Total density of state (TDOS) diagrams analysis has been also presented for title compound. Theoretical optimized geometric parameters and vibrational frequencies have been compared with the corresponding experimental data, and they have been shown to be in a good agreement with each other. Besides, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies have been found.

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