Infrared spectra of Br-(C2H2)(n) complexes

Mid-infrared spectra of Br--(C2H2)(n) (1 less than or equal to n less than or equal to 8) complexes have been recorded using vibrational predissociati on spectroscopy. Spectra of smaller clusters (n less than or equal to 6), f eature a single relatively narrow nu(3) absorption red shifted with respect to the free molecule absorption, and are consistent with interior solvatio n structures containing roughly equivalent C2H2 ligands bound end-on to the central Br-. Onset of the second solvation shell occurs at n = 7 and is si gnalled by the appearance of an additional isolated band situated between t he nu(3) absorptions of acetylene molecules bound directly to the Br- core and the one of free acetylene. (C) 2000 Elsevier Science B.V. All rights re served.