MOLECULAR-DYNAMICS AND THE STRUCTURE OF MACROCYCLES-SOLVENT ACETONITRILE INTERACTIONS

Microwave complex permittivities, epsilon = epsilon'- J-epsilon", are reported in the 1-90 GHz frequency range for the macrocycles 18-crown -6 (18C6) and 15C5 added to acetonitrile in stoichiometric proportions , in the solvent CCl4 at 25-degrees-C. Digitized infrared spectra of t he 'CN stretch' v2 vibration of acetonitrile for the same systems are reported in the 2300-2200 cm-1 spectral region. The macrocycle 12C4 ad ded to CH3CN has also been investigated in the infrared. Both the diel ectric relaxation and infrared results are interpreted in terms of mac rocycle-acetonitrile interactions, probably involving a methyl-hydroge n to ethereal-oxygen interaction. These interactions with CH3CN dimini sh in strength according to the sequence: 18C6 > 15C5 > 12C4.