Hydrogen bonding in 2-propanol. The effect of fluorination

Abstract

Fourier transform infrared (FTIR) spectra at thermal equilibrium and in seeded, pulsed slit jet expansions of 2-propanol(TP), 1,1,1-trifluoro-2-propanol (TFIP), and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) reveal dimers, oligomers, and large clusters as well as conformational isomerism of the monomers. The assignments are supported by hybrid density functional calculations. The effect of methyl group fluorination on OH frequency shift and intensity enhancement, torsional energetics, hydrogen bond strength, and cluster stability trends is investigated. HFIP promises to be a valuable prototype for spectroscopic studies of intramolecular torsional isomerization dynamics (as already shown in Quack, M. Faraday Discuss. Chem. Sec. 1995, 102, 104-107) and its coupling to intermolecular hydrogen bonding.