A relationship between the molecular polarizability, molecular dipole moment and atomic electronegativities in AB and AB_n molecules

Electronegativity equalization considerations applied to diatomics and AB_n molecules of C_nv, symmetry lead to a simple relationship between the static molecular dipole moment m₀, the static polarizability α along the principal axis and the electronegativity difference Δ_X between atoms A and B. The relationship is α = m₀ R/Δ_X where R is the bond length (or height in the case of AB_n). Ab initio calculations are used to assess this equation. For single bonds it is found that Δ_X is remarkably constant over a range of bond lengths, or moderately changing at most. However, Δ_X is found to be sensitive to valence coordinates that can modify the hybridization of the atoms. For equilibrium structures the electronegativity differences determined in this work are found to be within the range spanned by other scales.