The solid-state structures of 1-R-2,2-dimesitylethenols (R = H, Me, Et, i-Pr, t-Bu (1a-e)) and of 1,1-dimesitylethylene (4) were determined by X-ray diffraction. Enol la displayed tetramers of four crystallographically independent molecules in the unit cell, and lb crystallized with an EtOH molecule. As the bulk of R is increased, the C=C bond length increases, the R—C═C bond angle (α4) opens from 118.1° (1a) to 133.2° (1e), the RCO bond angle closes from 118.7° (1a) to 107.4° (1e), and the torsional angles ϕ1 (of the Ar group cis to the OH) and ϕ2 (of the aryl group trans to the OH) increase. α4 is linear in Taft's Es steric parameter. These trends are reproduced by MM2(85) calculations. Intermolecular enol-enol and enol-EtOH and intramolecular π (Ar)-HO hydrogen bonding are observed. The potential energy surface for 1,1-diphenylethylene (8) was calculated by molecular mechanics, and a propeller conformation with ϕ1= ϕ2= 40° is the lowest energy conformer. The calculated enantiomerization barriers for correlated rotations of zero-, one-, and two-ring flips are 12.9, 1.2, and 3.0 kcal mol-1. In the calculated transition state for the zero-ring flip, both rings are puckered. The Cambridge Structural Database gave 116 crystallographically independent molecules with the Ar2C═CR1R2 subunit. The ϕ1 vs ϕ2 angles for the 1,1-diarylethylenes were superimposed on the calculated surface for 8 in a conformational map. Experimental points concentrate around the calculated minimum and are absent in the vicinity of the (0°, 0°) region. When R1 and R2 differ much in bulk, the points prefer to concentrate around (0°, 90°) and (90°, 0°) diagonal whereas when the bulk of R1 resembles that of R2, many points concentrate along the diagonal between (40°, 40°) and (90°, 90°). By the crystal structure correlation principle, the one-and the two-ring flips are clearly favored over the zero-ring flip. Trimesityl-substituted systems are displaced toward the (90°, 90°) region compared with other triarylvinyl systems. Correlations between the bond angle ArCAr and the sum ϕ1 + ϕ2 and between the C—Ar bond length and the bond angle ArC═C were found.