Overlap properties of chemical bonds in generic systems including unusual bonding situations.

Chemical bond is a ubiquitous and fundamental concept in chemistry, in which the overlap plays a defining role. By using a new approach based on localized molecular orbitals, the overlap properties, e.g., polarizability $${\overline{\upalpha}}_{\mathrm{OP}}$$ , population pOP, intra $${\mathrm{J}}_{\mathrm{OP}}^{\mathrm{intra}}$$ , and inter $${\mathrm{J}}_{\mathrm{OP}}^{\mathrm{inter}}$$ repulsions, and density ρOP, of polyatomic systems were calculated, analyzed, and correlated. Several trends are shown for these properties, which are rationalized by the balance of some well-known effects, such as, electron donor/withdrawing character and electronegativity. The overlap properties of unusual bonds are also analyzed, revealing an OZn4(OOCH)6 structure with four equivalent Zn–O chemical bonds with overlap properties like the O–O bond in H2O2, while in protonated methane $$\mathrm{C}{\mathrm{H}}_5^{+}$$ , it is observed that a CH3⋯ $${\mathrm{H}}_2^{+}$$ bond pattern at the equilibrium structure changes to a $$\mathrm{C}{\mathrm{H}}_3^{+}$$ ⋯H2 pattern upon dissociation. Charge-shift resonance energies, atom-in-molecule properties, and the lone-pair-bond-weakening effects are related to the overlap properties, which can provide alternative views and insights into chemical bonds.