Substituent effects on the charge density in the formyl group

SCF wavefunctions with similar extended Gaussian bases for the series HCOX with X = H, OH (syn and anti), NH₂, CN, and F yield closely similar charge deformation density maps in the formyl region of all six molecules. The differences, measured by moments of partitioned atomic deformation densities, correlate almost linearly with the Hammett substituent parameters σ_I and σ_R of the several substituents X. However, systematic deviations, especially in the carbon fragment, suggest the need for modified values of the inductive parameters σ_I for the correlation of these molecular charge densities.