Twofold and Threefold Sinusoidal Patterns in Coupled Molecular Motions of 184,025 Structures of Phenylethane, Nitroethane, and Carboxylate Derivatives.

Abstract

Scatter plot analyses for 14,169 phenylethanes of the substructure Cβ-CαH2-Ph with three open coordination positions at Cβ and 150,568 phenylethanes of Cβ-CαHX-Ph with an additional open coordination position X at Cα have been performed, based on searches in the Cambridge Structural Database. The correlation of rotation angle ψ = Cβ-Cα-Ci-Co with a pyramidalization angle θ = Co-Co'-Ci-Cα in a 360° rotation about the bond Cα-Ci reveals a sinusoidal pattern with three maxima and minima, whereas the correlation of rotation angle ψ with bond angle ω = Cβ-Cα-Ci and bond length d = Cβ-Cα results in sinusoidal patterns with two maxima and minima. A total of 3993 nitro derivatives of the substructure Cβ-CαHX-NO2 confirm the results and show that atoms Ci/Co/Co' in the phenyl compounds can be replaced by atoms N/O/O' without any change in the two- and threefold patterns. In 15,295 methyl acetates of the substructure Cβ-CαHX-C'(═O)OMe, pyramidalization of the group CαC'(═O)OMe results in a chiral flat tetrahedron with four different corners. (Rθ)/(Sθ) selectivity in the configuration of the tetrahedron is induced by the bonds Cα-Cβ, Cα-H, and Cα-X, emanating from the tetrahedral center Cα. It is surprising that bonds as different as Cα-Cβ, Cα-H, and Cα-X (X = H, C, N, O, S, etc.) give almost the same induction intensities.