Vibrational spectroscopic (FTIR and FT-Raman), first-order hyperpolarizablity, HOMO, LUMO, NBO, Mulliken charge analyses of 2-ethylimidazole based on Hartree–Fock and DFT calculations

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 134; pp. 493 - 501
• Main Authors: Arivazhagan, M., Manivel, S., Jeyavijayan, S., Meenakshi, R.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05-01-2015
• Subjects: 2-Ethylimidazole; Ab initio; DFT calculations; FT-Raman; FTIR; Imidazoles - chemistry; Models, Molecular; Quantum Theory; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Ab initio; FT-Raman; FTIR; 2-Ethylimidazole; DFT calculations
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2014.06.108

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•Imidazoles have important feature of a variety of medicinal agents.•The optimized geometries and harmonic vibrational wavenumbers of 2-ethylimidazole have been carried out.•Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed.•Mulliken's net charges, HOMO–LUMO analysis and several thermodynamic properties were performed.
The FTIR and FT-Raman spectra of 2-ethylimidazole (2EIDZ) have been recorded in the region 4000–400cm−1 and 3500–50cm−1, respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimized molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by ab initio Hartree–Fock (HF) and density functional theory (DFT/B3LYP) methods with 6-311++G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of 2EIDZ is also reported based on total energy distribution (TED). The values of the total dipole moment (μ) and the first-order hyperpolarizability (β) of the compound were computed. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. Besides, HOMO and LUMO analysis, Mulliken’s charge analysis and several thermodynamic properties have been calculated.