Spectroscopic (FTIR, FT-Raman, 13C and 1H NMR) investigation, molecular electrostatic potential, polarizability and first-order hyperpolarizability, FMO and NBO analysis of 1-methyl-2-imidazolethiol

Abstract

In this work, experimental and theoretical study on the molecular structure and vibrational spectra of 1-methyl-2-imidazolethiol (MIME) were presented. The vibrational frequencies of the title compound were obtained theoretically by ab initio HF and DFT (B3LYP/LSDA) employing 6-311G (d,p) and 6-311++G(d,p) basis sets and compared with experimental spectral bands (FTIR and FT-Raman). The thermodynamic properties of the studied compound have been computed at different temperatures. The atomic charges and charge delocalization of the molecule have been analyzed by natural bond orbital (NBO) analysis. The reactivity sites are identified by mapping the molecular electrostatic potential (MESP) surface. Electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Besides, 13C and 1H nuclear magnetic resonance (NMR) chemical shifts of the molecule in chloroform solvent calculated using the Gauge-Independent Atomic Orbital (GIAO) method are found to be in good agreement with experimental values.