Infrared spectra of the very weak H₂-HF and O₂-HF complexes in solid neon

Very weak, hydrogen bonded complexes of molecular hydrogen and oxygen with HF have been prepared by condensing the neon diluted reagents at 4-5 K. Infrared spectra of the H₂-HF complex revealed a ν_s (HF) mode at 3938 cm^-1 and ν^c(H₂) mode at 4155 cm ^-1 which are red shifted from isolated molecule values in agreement with theoretical predictions. Increasing the HF concentration produced a 1:2 complex, H₂-(HF)₂. Similar experimental results were obtained for molecular oxygen complexes using HF and DF; the oxygen fundamental in this complex, however, exhibited a 6 cm^-1 blue shift. Spectra of these complexes in argon matrices showed that argon is not an effectively inert medium for very weak complexes where interaction with the solid argon environment is competitive with the H₂-HF and O₂-HF interactions.