Weak intramolecular OH⋯π hydrogen bonding in methallyl- and allyl-carbinol

We have recorded the third OH-stretching overtone region of vapor phase methallyl- and allyl-carbinol with intracavity laser photoacoustic spectroscopy to investigate the effect of the methyl group in methallyl carbinol on the weak intramolecular OH⋯π hydrogen bond. We have used atoms in molecules theory, non-covalent interactions calculations and natural bond orbital analysis to describe the intramolecular OH⋯π hydrogen bond. An increased intramolecular interaction was predicted and confirmed experimentally by an observed larger redshift of the OH-stretching overtone transition of the most abundant conformer of methallyl carbinol relative to that of the corresponding conformer of allyl carbinol.