Brunner, Henri and Ikeshita, Masahiro and Tsuno, Takashi (2021) Chirality of the Conformation Attacks the Planarity of the sp(2) Carbon Atom in a Covalent Bond. JOURNAL OF ORGANIC CHEMISTRY, 86 (15). pp. 10414-10419. ISSN 0022-3263, 1520-6904
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The correlation of the rotation about the bond C'-C-alpha and the pyramidalization of the sp(2) hybridized carbon atom C' and its three bonding partners to a flattened tetrahedron was investigated for the substructure C-beta-C alpha H-C'(=O)-OMe. A search in the Cambridge Structural Database (CSD) gave 15,295 structures with a substituted methyl acetate group at the end of the molecules. The scatter plot of the rotation angle psi = O=C'-C-alpha-C-beta versus the pyramidalization angle theta = O(MeO)C'C-alpha and the psi/theta(av) curve show an unusual undulating pattern with three maxima and minima for a 360 degrees rotation about the bond C'-C-alpha. There is no net chiral induction from the (M-psi)/(P-psi) conformations of the bond C'-C-alpha to the (R-theta)/(S-theta) configurations of the flattened tetrahedron because the contributions of the three maxima and minima cancel each other. The wavelike psi/theta(av) curve demonstrates that the rotation about the bond C'-C-alpha and the pyramidalization of the group C'(=O)(OMe)C-alpha are not independent processes. They are coupled with each other in one common molecular motion. The psi/theta(av) curve appears as the third harmonic of a sinusoidal fundamental frequency. DFT calculations of the propanoate anion, methyl propanoate, and methyl 2-methylpropanoate confirm the results of the CSD search.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CAMBRIDGE STRUCTURAL DATABASE; CHEMICAL-REACTION PATHS; CRYSTAL; DISTORTION |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Aug 2022 12:01 |
| Last Modified: | 17 Aug 2022 12:01 |
| URI: | https://pred.uni-regensburg.de/id/eprint/46641 |
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