IR STUDIES OF VANDERWAALS INTERACTIONS ON PERFLUORO-TERT-BUTYL ALCOHOL OH .2. COMPLEXES WITH ACETONITRILE

The intermolecular effects on the OH stretching mode of perfluoro-t-butanol/acetonitrile (PFTB/AN) complexes have been studied in the vapour phase, different low temperature matrices, liquid and different solvents and are compared with effects on PFTB monomers. The experiments demonstrate that IR spectroscopic studies of intermolecular interactions give much detail and need a sensitive knowledge of the different parameters. In matrices cooperativity effects of PFTB associates as well as of acetonitrile cluster on the PFTB/AN H-bond complex are observed. Matrices and solvents have different influences on the PFTB/AN complex and on PFTB monomers. Different solvents change the halfwidths Δν 1 2 of monomers and PFTB/AN in a similar way, proportional to the frequency shift Δν (interaction energies). The complex halfwidth and solvent induced Δν 1 2 appear to be additive. dΔν 1 2/dT is proportional to δν, with different proportionality factors for monomers and the complexes. Differences are observed between PFTB monomers and the AN H-bonded complex which may be explained as follows: the direct intermolecular potentials act between monomers, whereas for the H-bond complexes the distance in the H-bond potential between OH and AN is changed due to a solvent effect. © 1990.