Non-covalent Interaction of Heteroaromatic: Rotational Spectroscopy of the Thiazole-Formic Acid Complex^†

The characteristics of non-covalent linkages between thiazole and formic acid were explored by pulsed jet Fourier transform microwave spectroscopy supplemented with quantum chemical calculations. Rotational fingerprints of the thiazole∙∙∙HCOOH and thiazole∙∙∙HCOOD species were successfully measured in the supersonic expansion, both exhibiting ¹⁴N quadrupole coupling hyperfine structure. The observed conformation has C_s symmetry, controlled by a predominant O−H∙∙∙N hydrogen bond and an additional C−H∙∙∙O hydrogen bond. The property of intermolecular non-covalent interactions emerging in the complex has been ulteriorly elucidated by implementing Johnson's non-covalent interaction analysis and the symmetry adapted perturbation theory analysis.