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

Metin Bilge,Cemal Parlak,Hasan Bircan,Özgür Alver

doi:10.4314/bcse.v26i2.11

Abstract

The normal mode frequencies and corresponding vibrational assignments, 1H and 13C NMR chemical shifts and structural parameters (bond lengths, bond and dihedral angles) of 2-[(1E)-2-aza-2-(5-methyl(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, 2mpe-4bb 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 Bull. Chem. Soc. Ethiop. 2012, 26(2), 279-285.DOI: http://dx.doi.org/10.4314/bcse.v26i2.11

Highlights

Compounds with the structure XC=NY are known as Schiff bases, which are usually synthesized from the condensation of primary amines and active carbonyl groups
For the NMR calculations, the title compound was first fully optimized at Hartree Fock (HF) and Density functional theory (DFT) methods using 6-31G(d) basis set in chloroform with the IEFPCM method [14,15,16,17] (Table 1)
The optimized structural parameters by HF and DFT with 631G(d) basis set are listed in Table 3 and compared with available experimental crystal geometry of 2mpe-4bb [9]

Summary

Introduction

Compounds with the structure XC=NY are known as Schiff bases, which are usually synthesized from the condensation of primary amines and active carbonyl groups. We have calculated structural parameters, thermodynamics functions, vibrational frequencies together with PED, HOMO and LUMO data, 1H and 13C NMR chemical shifts of 2mpe-4bb using HF and DFT methods with 6-31G(d) and 6-311++G(d,p) basis sets and compared with available experimental values.

Results

Conclusion