The molecular structure of 2-trifluoromethylphenol has been
determined by gas-phase electron diffraction.
The analysis, aided by constraints from ab initio molecular
orbital calculations, yielded the following bond
lengths (r
g) and bond angles:
(C−C)Ar,mean, 1.395 ± 0.004 Å; C−C(F3),
1.510 ± 0.005 Å; C−O, 1.362 ±
0.011 Å; (C−F)mean, 1.358 ± 0.006 Å;
∠O−C1−C2, 121.0 ± 1.2°; ∠C−O−H,
105 ± 6°;
∠C(F3)−C2−C1,
120.7 ± 0.8°; (C−C−F)mean, 113.2 ± 0.3°;
CF3 torsion, 10.1 ± 0.8°. Weak intramolecular
bifurcated hydrogen
bonding between the hydroxy hydrogen and two of the CF3
fluorines is indicated by the H···F nonbonded
distances 2.05 ± 0.06 and 2.42 ± 0.06 Å. Compared with the
freely rotating CF3 group in trifluoromethylbenzene, the well-defined conformer of 2-trifluoromethylphenol
indicates the constraining effect of hydrogen
bonding.