Unveiling the structural and energetic properties of thiazole-water complex by microwave spectroscopy and theoretical calculations

Abstract The structure and non-covalent bonding features of the complex of thiazole and water were studied by using supersonic jet Fourier transform microwave spectroscopy and theoretical calculations. One isomer was observed which corresponds to the global minimum of the complex predicted theoretically. The rotational spectra of 9 additional isotopologues, including 5 mono-substituted heavy atoms of thiazole (34S, 13C and 15N), and 4 water isotopic species (H218O, DOH, HOD and D2O), were also measured and analyzed. The experimental spectroscopic parameters were used to determine the structural parameters of the observed isomer. Theoretical analyses based on quantum theory of atoms in molecules and natural bond orbital revealed that the two moieties are linked by a N···H—O hydrogen bond. The total interaction energy of the complex is calculated to be −25.1 kJmol−1 with electrostatics being the major term according to energy decomposition analysis.