Knowledge Bank

We have continued the investigation of infrared absorption intensities of moderate sized oxygen-containing organic molecules, begun with our report here last year of $CH3OH$ intensities, through intensities for other alcohols, ethers, aldehydes and now ketones. These investigations have included both experimental measurements of the vibrational band intensities and interpretation based on the atomic polar tensors. The latter has included investigation of transferability (moderately good, in general), and attempts at interpretations based on results from ""ab initio"" Gaussian 70 4-31G quantum mechanical calculations of the atomic polar tensors. Interpretation of the latter results in terms of “charge”, “charge flux”, and “hybridization” contributions has now begun to yield patterns of results for this series of related compounds that promise to be a real guide to chemical intuition and to the prediction of intensities for even larger molecules.