The polar properties of valence bonds

Arguments based on bond-stretching frequencies, nuclear quadrupole coupling constants and bond lengths indicate that bonds having the same strength factor can have different electronic structures. It is then argued that a more useful probe for obtaining an insight into bond character is provided by infrared band intensities which can be analyzed to yield values for the constants occurring in bond moment functions. A new bond moment theory, in which the concept of “rehybridization moments” is introduced, is described. Using this theory, self-consistent values are obtained for the bond moment constants governing the band intensities for the molecules HCN, C₆H₆ and C₂H₄.