2-nitroimidazole derivative studied by means of 35Cl-NQR spectroscopy and molecular dynamics simulations

Cl-35 nuclear quadrupole resonance as well as quantum chemical calculations were applied to study electronic structure and molecular dynamics of the imidazole derivative 1-(2-hydroxy-3-chloroprophyl)-2,3-dinitro-5-methyl-imidazole. The spectra of this compound taken at 77 and 293 K show only one line, which means that there are no physically inequivalent positions of the chlorine atoms in the elementary cell. The line width was of about 28 kHz at 77 K and the relaxation time was about 320 ms at liquid-nitrogen temperature and about 8 ms at room temperature. As follows from the spin-lattice relaxation time measurements performed for the compound studied, in the range 77-200 K the libration mechanism of molecular vibrations is active, while above 200 K the activation process related to reorientation of the CH2Cl group begins. The activation energy is 18.82 kJ/mol. The activated process of the CH2Cl group reorientations exerts rather insignificant effect on the averaging of the electric field gradient in the vicinity of the resonant Cl-35 nucleus.