In-Depth Theoretical Investigations of Borazine's Aromaticity: Tailoring Electron Delocalization through Substituent Effects.

The current study investigates the influence of several R substituents (e.g., Me, SiH, F, Cl, Br, OH, NH, etc.

modelling of chelate stabilized tetrylene derivatives.

The steric and electronic effects of specific ligands can play crucial roles in stabilizing unsaturated tetrylene species. In this work, hybrid density functional theory (DFT) methods, quantum theory of atoms in molecules (QTAIM) investigations and natural bond orbital (NBO) calculations are employed to evaluate the stabilization of low-valent E(ii) centers (E = Si, Ge, Sn, Pb) through the chelating effect generated by an electron-rich ligand containing the P[double bond, length as m-dash]C-P[double bond, length as m-dash]X moiety (X = O or S). Based on several types of analyses, such as the bond dissociation energy (BDE) or the interplay between attractive (, charge-transfer) and repulsive (, Pauli-exchange) effects, we highlight that the stabilization energy induced by chelation is up to 70 kcal mol for silylenes, yet slightly decreases within the heavier analogues.