Abstract
Η-bonding between Pyrrolidon and different aczeptors is investigated. Different attempts of mathematical refinements are not much better than the common corrections of the overlapping H-bond-band. Pyrrolidon shows in different solvents only a dimerisation. Therefore the selfassoziation of the donor can easy mathematically separated from the donor-aczeptor-interaction. The series different aczeptors gives small differences between the amidgroup as donor and phenol as donor. This sequence determined by the equilibrium constants with the overtone spectra is in the case of Pyrrolidon the same than the series determined by the frequency-shift of the H-bond-band in the fundamental region.