Abstract Tautomerism is one of the most important phenomena to consider when designing biologically active molecules. In this work, we use NMR spectroscopy, IR, and X-ray analysis as well quantum-chemical calculations in gas phase a solvent study tautomerism 1- (2-, 3- 4-pyridinecarbonyl)-4-substituted thiosemicarbazide derivatives. The tautomer containing both carbonyl thione groups turned out...
