Theoretical Study of Molecular Structure, Conformational Analysis, and Vibrational Spectra for Some Diazabicyclo Derivatives

                The computational chemistry in recent years becomes of great importance in many chemical and pharmaceutical scientific fields.This thesis involves a theoretical study for compounds contain four
saturated diazabicyclo molecules with the presence of two atoms of nitroges (N-N) as a bridgehead. These molecules are 1,3diazabicyclo[1.1.0]butane (DABCB), 1,4-diazabicyclo[2.1.0]pentane
(DABCP), 1,4-diazabicyclo[2.2.0]hexane (D'A'B'C'H'), and 1,5diazabicyclo[3.1.0]hexane (DABCH). Furthermore this study included another group also consist four molecules bicyclo[1.1.0]butane,
bicyclo[2.1.0]pentane, bicyclo[2.2.0]hexane, and bicyclo[3.1.0]hexane which consider as a parent. Most of these molecules are unstable.This theoretical study was done employing the density functional theory
DFT with B3LYP / high basis set 6-311G ++ (d,p), using Gaussian program 09. Calculation were done to obtain several properties such as equilibrium optimize geometry, total energy, dipole moment, partial
atomic charge, potential energy curve, and the energy of molecular orbital. For the diazabicyclo molecules the vibrational spectra (frequencies, IR,and Raman intensities) with its reliable assignment for each 3N-6 fundamental vibrational was acquired.  The most stable conformer was evaluated, from the potential energy curve as following:-                                                                                       
 BCB and DABCB         →    (puckered conformation).
 BCP and DABCP          →    (envelop conformation).
 B'C'H' and D'A'B'C'H'   →    (sofa conformation).