Infrared intensities as a quantitative measure of intramolecular interactions. Part XXXVII. 1,1-Disubstituted ethylenes

Infrared intensities of the ν(CC) vibration of 1,1-disubstituted ethylenes are proportional to the sum of the squares of the σ0R constants of the substituents. This result is rationalised in terms of the contributions of the substituents to the rate of change of dipole moment with normal co-ordinate. CNDO/2 MO calculations of charge densities and intensities are also reported.