Correlation analysis of characteristic infrared spectral data of hydantoin derivatives: evidence for vibrational coupling

Abstract The characteristic vibrations ( ν CO and ν CC ) of a large number of hydantoin derivatives are reported. Especially the very fine correlations ν CO (sym) versus ν CO (asym) ( r 2 =0.985) but also successful correlations of the vibration wave numbers to HAMMETT's substituent constants and some other experimental parameters (p K s , OxPot, RedPot) as well, corroborate reassignments of previously obtained results [Monatsh. Chem. 92 (1961) 361] and prove the doublet obtained in the region of the CO stretching vibrations to be the symmetrical and anti -symmetrical vibrational modes of a mechanically coupled system of two quasi -symmetrical CO bonds.