High-Resolution Infrared Spectroscopy of HCN−Agn(n1−4) Complexes Solvated in Superfluid Helium Droplets.

High-resolution infrared spectroscopy has been used to determine the structures, C−H stretching frequencies, and dipole moments of the HCN−Agn(n1−3) complexes formed in superfluid helium droplets. The HCN−Ag4cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN−Agncomplexes are structurally similar to the previously reported HCN−Cunclusters, with the exception of the HCN−Ag binary complex. Although the interaction between the HCN and the Agnclusters follows the same trends as the HCN−Cunclusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction. [ABSTRACT FROM AUTHOR]