Infrared spectra of OC–HX hydrogen-bonded complexes in solid argon

Abstract

The hydrogen-bonded complexes OC–HX (X=F, Cl, Br) has been prepared by condensing Ar/HX and Ar/CO reagent mixtures at 12 K. FTIR spectra of the complexes are characterized by strong H–X absorptions (νs) displaced below the isolated HX fundamental, strong C–O absorptions displaced above the isolated CO fundamental, and sharp degenerate librational modes (νl) in the far infrared. Observation of a single degenerate νl mode indicates linear structures for the complexes. The displacements Δνs and ΔνCO for the complexes decrease in magnitude in the series HF≳HCl≳HBr in direct relationship with the trend in hydrogen bonding strength for the hydrohalic acids.