Theoretical Analysis of Stereoelectronic Effects in the 2,4,6-Trihalo-1,3,5-trioxane and 2,4,6-Trihalo-1,3,5-trithiane Conformers

Abstract

This research aimed at exploring the conformers stabilities of 2,4,6-trihalo-1,3,5-trioxane and 2,4,6-trihalo-1,3,5-trithiane molecules at the LC-wPBE/6-311+G(d, p) theory level. To this goal, estimations of the total energies and frontier orbitals energies of the axial and equatorial conformations were first done for the afore-mentioned molecules. C–E (E = O, S), C–X (X = F, Cl), and C–H bonds lengths were calculated and these variations were explained with negative hyperconjugative anomeric effects. In addition, QTAIM analysis was used to illustrate the character of these bonds. The partitioning of the total electronic energy E(tot) into Lewis EL and non-Lewis ENL parts was performed using the concept of natural bond orbital (NBO) analysis. Then, the natural Coulomb electrostatic (NCE) potential energies, total energies into Lewis components, and total steric energies were estimated. Proton chemical shift and C–H spin–spin coupling values (J(C–H)) of the studied molecules were calculated.