GAS-PHASE IR-SPECTRA OF SYSTEMS WITH INTRAMOLECULAR HYDROGEN-BONDS

The IR spectra of intramolecular hydrogen bonds in ortho Mannich bases have been measured in the gas phase and in diluted CCl4 solutions. It is demonstrated that the intramolecular hydrogen bonds are stable bot h in the gas phase and in CCl4 solutions. The hydrogen bonds in the ga s phase are weaker but the nu(s)(OH) bands are still broad with a half width of about 400-500 cm-1. It demonstrates that the coupling with in ternal modes of a molecule is a sufficient condition for such band bro adening. Spectral moments of nu(s)(OH) bands were determined and corre lated with DELTApK(a) values both in the gas phase and in CCl4 solutio ns.