Theoretical molecular structure, vibrational frequencies and NMR investigations of 2-[(1E)-2-aza-2-(5-methyl(2-pyridyl)ethenyl)]-4-bromobenzen-1-ol

The normal mode frequencies and corresponding vibrational assignments, ¹H and [sup.13]C NMR chemical shifts and structural parameters (bond lengths, bond and dihedral angles) of 2-[(1E)-2-aza-2-(5methyl(2 -pyridyl)ethenyl)]-4-bromobenzen-1-ol (2mpe-4bb) Schiff base compound have been theoretically examined by means of Hartree-Fock (HF) and Becke-3-Lee-Yang-Parr (B3LYP) density functional methods with 6-31G(d) and 6-311++G(d,p) basis sets. Furthermore, reliable vibrational assignments have made on the basis of potential energy distribution (PED) calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 2mpe-4bb have been predicted. Theoretical results have been successfully compared with available experimental data in the literature. Regarding the calculations, 2mpe4bb prefers enol-imine form and DFT method is superior to HF approach except for predicting bond lengths. KEY WORDS: Schiff bases, Normal mode frequencies, HF, DFT, NMR