Document Type : Original Article

Authors

• Vahidreza Darugar ¹
• Mahmood Akbari ²
• Ali Reza Berenji ³

¹ Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Iran

² UNESCO-UNISA-ITL/NRF Africa Chair in Nanoscience and Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P.O. Box 392, Pretoria, South Africa

³ Department of Chemistry, Faculty of Science, University of Gonabad, Gonabad 96919, Iran

Abstract

The tautomerism and intramolecular hydrogen bond of 5-Bromo-salicylideneimino-ethylimino-pentan-2-one (BrSEIPO) was studied by theoretical method. The tautomeric mole fraction calculations show that the L4 and L3 forms are the more stable form of SEIPO with 99.29% and 0.71% values in gas phase and for L4 form more than 67.91% in solution phase. It can be seen that with increasing the polarity of the solvent the molar fractions of two more stable forms are changed. The molar fraction of L4 and L3 forms decreases and increases, respectively Besides, the mole fraction of L3 tautomer becomes in the range from ca. 0.87% to 33.69%, while the polarity of solvent increases.By comparing the value of the geometrical results (RO…N, RN–H, O…H, θOHN), AIM results (ρBCP, ∇2ρBCP, HBCP, H-bond energy), and spectroscopic results (νNH, γNH, δOH) it can be see that the intramolecular hydrogen bonding (IHB) of BrSEIPO is stronger than that in salicylideneimino-ethylimino-pentan-2-one (SEIPO) and 4-amino-3-penten-2-one (APO).

Keywords

• Tetradentate Schiff bases
• Tautomerism
• Density functional theory