A. D. Richardson, K. Hedberg
Jun 13, 2001
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Influential Citations
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Journal
Journal of Molecular Structure
Abstract
Abstract There are 14 possible rotational conformers of 3-fluoropropan-1-ol, based on the assumption of three potential minima for rotation about single bonds. Of these, only the g G − G form ( g ,G= gauche , a ,A= anti ) where the sequence indicates rotation around the C–O, the C O –C, and the C–C F bonds, with the minus sign indicating clock-wise rotation has the hydrogen and fluorine atoms in position for formation of a hydrogen bond. Analysis of gas-phase electron-diffraction data obtained at a sample temperature of 20°C indicates the dominant form to be a GG (41 (2σ=19)% of the sample). The hydrogen-bonded form g G − G comprises 2 (19)% of the sample. These values reflect the assumption that the amounts of the remaining components of the system exist in proportions given by the results of ab initio (B3LYP/6-311+G(3d,2p)//B3LYP/6-31G(d)) calculations. Weighted average parameter values ( r g /A, ∠ g /deg) for all forms are r (C–C)=1.528(3), r (C 1 –C 2 )− r (C 2 –C 3 )=0.066(12), r (C–H)=1.115(4), r (C–O)=1.380(8), r (C–F)=1.450(6), ∠(COH)=105.9(assumed), ∠(CCF)=109.7(8), 〈∠(CCC), ∠(CCO)〉=111.8(6), ∠(COH)−∠(COH)=3.1(assumed), ∠(CCH)=109.4(7). Torsion-angle parameters could not be refined. Weighted average theoretical torsion angles for conformers with G or G − orientations are ∠(OCCC)=63.2(3), and ∠(CCCF)=61.0(3). Ab initio calculations at several levels of theory with several basis sets predicted substantially different amounts of the g G − G form. Best agreement with experiment was given by the B3LYP/6311++G(3d,2p)//B3LYP/6-31G(d) calculations.