pdf Electronic Structure and Reactivity Analysis of Bromocyclohexane, Chlorobenzene, and Iodobenzene Using Density Functional Theory

Huda M. Jawad, Ahlam M. Kadhim and Huda Talal Sulaiman

Abstract

Density functional theory study was carried out to investigate the electronic structure and vibration properties of bromocyclohexane, chlorobenzene, and iodobenzene. the calculations implemented in Gaussian 09.  The results showed infrared transmittance data provided key insights into functional groups and bond vibrations. Chlorobenzene and iodobenzene exhibit maximum absorption (or minimum transmittance) at around 700 cm¹, corresponding to C-X (carbon-halogen) stretching vibrations, particularly C-Cl and C-I bonds. However, hexane bromosate exhibits a significant absorption at about 2900 cm^-1, which is associated with C-H stretching at SP3-hybridized carbon atoms (a characteristic feature of saturated aliphatic structures such as cyclohexane). In contrast, the reduced mass values provided evidence of atomic contributions to specific vibrational modes, particularly in heavy atom interactions. The reduced masses reach 6 atomic mass units (a.m.u) of Chlorobenzene and Iodobenzene, which is nearly the reduced mass between two carbon atoms, and reduced masses reach 1.3(a.m.u) for Bromocyclohexane.  The positive charge value is (hydrogen - iodine - chlorine - bromine) while the negative values are for carbon. Iodine, boron, and chlorine atoms appear positively charged in Mulliken charge analysis, primarily due to differences in electronegativity and bond polarity. Together, these computational results contribute to the understanding of the molecule's electronic structure, stability, and reactive behavior, and provide information for its potential applications in pharmaceutical and materials science.