The Studies of Structure of 2N‐(3‐phenyl‐allyl‐)(5‐phenyl‐[1,3,4] Thiadiazol‐2‐yl) Amine in Solution

2N‐(3‐phenyl‐allyl‐)(5‐phenyl‐[1,3,4] thiadiazol‐2‐yl) amine was studied by means of the 1 H, 13 C, 15 N NMR spectroscopy and DFT calculations. On the basis of the one‐dimensional 1 H, 13 C, 15 N‐NMR and two‐dimensional 1 H‐ 13 C HMQC, 1 H‐ 13 C HMBC, 1 H‐ 15 N HMQC, 1 H 1 H NOESY, 1 H 1 H COSY correlation spectra the amine‐type and the imine‐type tautomers have been determined in the solution. Variety of structural forms including: biradical, ionic–biradical, and ionic structures of the amine‐type a and of the imine‐type b , c tautomers exist in the solution. According to the DFT computations the differences in the total energy between a and b , a and c , and b and c tautomers are equal to 1.5 kJ/mol, 1.2 kJ/mol, and 0.3 kJ/mol, respectively.