Conformational analysis of 2,5-diaryl-4-methyl-2,4-dihydro-3H-1,2,4-triazol-3-ones: Multinuclear NMR and DFT calculations

Abstract

Conformational exploration of five 2,5‐diaryl‐4‐methyl‐2,4‐dihydro‐3 H ‐1,2,4‐triazol‐3‐ones has been carried out based on a combination of their NMR chemical shifts determined in CDCl 3 and the scrutiny of their computed relative energies and absolute shieldings calculated at the DFT/GIAO/B3LYP/6–311++G(d,p) level. The very flat potential energy curves corresponding to the three relevant single bond rotations were explored by calculating the energy of the rotational barriers and comparing the experimental chemical shifts with those theoretically calculated in each rotamer by statistical analysis.