C—H···O hydrogen bonds in liquid cyclohexanone revealed by the νCO splitting and the νC–H blue shift

The presence of C—H···O hydrogen bonds in liquid cyclohexanone is concluded from a combined theoretical and vibrational spectroscopic study. The two bands present in the νCO region, clearly observed in the Raman spectrum, are assigned to ‘free’ and ‘bonded’ carbonyl groups from their temperature‐dependent and solvent‐dependent relative intensities. In addition, a band exhibiting the same intensity dependence in the νC–H region is tentatively assigned to the blue‐shifted νC–H···(O) mode.