¹⁷ O NMR spectra of twelve stable simple enois 1[Ar₂CC(R)OH, Ar = crowded aryl group, R = H (1c, Ar = Mes), Bu^t, m- and p-substituted aryl, mesityl] were measured in CDCl₃ and of six of them in [²H₆] DMSO. ¹³C spectra of all the enois were measured in both solvents. These are the first values measured for enois not strongly intramolecularly hydrogen bonded. The δ(¹⁷O) values in CDCl₃ are divided into three groups which parallel the steric bulk of R: (i) 70.5–74.9 when R = H; (ii) 84.1–87.4 when R =m- and p-substituted aryl; (iii) 93.0–98.5 ppm for R = Bu^t, mesityl (Mes). ΔδO =δ(¹⁷O)[[²H₆]DMSO]–δ(¹⁷O)[CDCl₃]= 7–10 for group (i), ca. 3 for group (ii) and –17 for trimesitylethenol 1l. IGLO calculations on CH₂CHOH (4) give a shallow parabola for the δ(¹⁷O)vs. the CC–O–H torsional angle θ plot, with maxima at θ= 0 and 180°(syn and anti planar conformations) and a minimum at θ= 90°. δ(¹³C-2) values show an approximate mirror-image change while δ(¹³C-1) changes slightly with θ. Calculation on the solvates 4·OSH₂ with syn, anti and perpendicular conformations show trends similar to those for uncomplexed 4 with upfield shifts of δ(¹⁷O, ¹³C-2) and downfield shift of δ(¹³C-1, ¹H) in all conformations. When the calculations also included the effect of the reaction field, the δ(¹⁷O) values of the perpendicular and anti conformations differ little from those of uncomplexed 4. PM3 calculations for four enois including 1c and 1l also show a minimum at θ= 90° and the plot of Δ_fH for 1c and 1lvs. θ resemble the calculated energy (by MP2/6-311 G**)vs. θ plot for 4. No correlation exists between the Ar–CC torsion angles or λ_max of the enols with δ(¹⁷O), but the polar effect of the α-substituent affects the δ(¹⁷O) values. The solvent effect is ascribed to OH–[²H₆]DMSO hydrogen bonding, accompanied by a conformational change from syn-periplanar in CDCl₃ to mainly anti-clinal in [²H₆]DMSO. A lower association with DMSO for bulkier Rs and an accompanying change of θ towards 90° qualitatively account for the ΔδO values. Several correlations between the δ(¹⁷O), δ(¹H) and δ(¹³C) shifts or of δ(¹³C) and Hammett's σ values were found.