Molecular structure and IR absorption spectra of perfluorinated aldehyde hydrates (n-CxF2x+1CH(OH)2, x = 1–4)

Structures and IR absorption spectra of the conformational isomers of perfluorinated aldehyde hydrates, n-CxF2x+1CH(OH)2, (x = 1–4) have been calculated using density functional theory (DFT) and compared to experimental FT-IR measurements. Two absorption peaks around 3600–3700 cm−1 were observed and are assigned to OH stretching modes of OH groups with, and without, intramolecular hydrogen bonding. For n-C3F7CH(OH)2, two absorption bands around 900–1000 cm−1 were observed in the experimental spectra, whereas only a single in-phase stretching mode of the (CF3)(C2F4CH(OH)2) and (C3F7)(CH(OH)2) bonds was calculated for each conformer. The experimental spectra were well described by composite spectra of the thermal equilibrium mixture of different conformational isomers of n-CxF2x+1CH(OH)2 calculated by DFT.