International Journal of Modern Chemistry, 2018, 10(1): 117-137 International Journal of Modern Chemistry ISSN: 2165-0128 Journal homepage: www.ModernScientificPress.com/Journals/IJMChem.aspx Florida, USA Article Molecular Properties of the Valence Isomers of Diazines: Density Functional Theory (DFT) and Møller Plesset (mp2) Methods IBRAHIM, Asiata Omotayo, OYEBAMIJI Abel Kolawole and SEMIRE Banjo* Department of Pure and Applied Chemistry, Faculty of Pure and Applied Sciences, Ladoke Akintola University of Technology, PMB 4000, Ogbomoso, Oyo State, Nigeria * Author to whom correspondence should be addressed; E-Mail:
[email protected] Article history: Received 20 February 2018, Revised 25 April 2018, Accepted 30 April 2018, Published 21 May 2018. Abstract: Density functional theory (B3LYP) and Moller-Plesset perturbation theory to the second order (MP2) methods with 6-31G(d),6-31+G(d,p), 6-311G (d,p), 6-311+G(d,p) and 6-311++G(d,p) basis sets have been used to investigate some diazine isomers. The equilibrium geometries, relative stabilities, strain energies, vibrational frequencies and global nucleophilicity indices for fifteen isomers are reported. The relative energies show that Dewar isomers (except 1,4-DBHD) are more stable compared to the Diazyl-isomers. The isomers with N-N and/or N-C bonds in the center are less stable, this is observed for both Dewar and Diazyl-isomers; therefore nitrogen atom(s) in the center of the isomers decreases the stability. Keywords: Diazines, relative stabilities, nucleophilicity index, quantum mechanical methods 1. Introduction Pyridazines are diazines group of compounds that are formally derived from benzene by the Copyright © 2018 by Modern Scientific Press Company, Florida, USA Int.