Infrared Spectra and ab initio Calculations for Fluoride-acetylene Clusters: F - -(HCCH)n, n=3 - 6

Infrared spectra and ab initio calculations are presented for gas phase clusters consisting of a fluoride anion attached to acetylene ligands. Spectra obtained in the C-H stretch region contain a single strong band, consistent with cluster structures in which roughly equivalent acetylene ligands are hydrogen bonded to a central fluoride anion core. Minimum energy structures predicted from ab initio calculations at the MP2 level of theory are highly symmetric with acetylene ligands equally spaced about a central fluoride anion core. The predicted H-bonded C-H stretching frequencies, after scaling to correct for anharmonicity, agree well with the experimental band positions.