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- Title
Synthesis and Characterization of Hypervalent Pentacoordinate Carbon Compounds Bearing a 7‐6‐7‐Ring Skeleton.
- Authors
Yamamoto, Yohsuke; Shi, Yuan; Masui, Takashi; Saito, Daigo; Inoue, Tatsuya; Sato, Hitomi; Dohi, Chisato; Muneta, Emiko; Shang, Rong; Nakamoto, Masaaki
- Abstract
To stabilize SN2 transition state‐like penta‐coordinate carbon species, triaryl‐substituted cationic carbon compounds bearing a moderately flexible 7‐6‐7‐ring skeleton with sulfur donors were synthesized and characterized. Electronic effects of para substituents (R=Cl, F, H, CH3, SMe, OMe) of the two equatorial aryl groups bound to the cationic central carbon were investigated systematically along with a planar bidentate thioxanthene derivative. X‐ray analysis on their solid‐state structures showed that the parent (R=H), chloro‐, fluoro‐ and methyl‐derivatives were tetracoordinate carbon (sulfonium) structures, while the p‐MeO and thioxanthenyl system were pentacoordinate carbocation structures. The Hammett substituent constants for the para substituents (σp+) correlates well with the bonding in these compounds. The methylthio‐derivative with intermediate Hammett substituent constants (p‐MeS; σp+=−0.60) showed a tetracooridnate solid‐state structure, though solution UV‐Vis properties suggested the presence of a penta‐coordinate structure. These findings amount to the first unambiguous solution evidence of the hypervalent apical 3c–4e interactions in pentacoordinate carbon compounds.
- Subjects
CARBON compounds; SKELETON; ARYL group; POLAR effects (Chemistry); CARBOCATIONS
- Publication
Chemistry - A European Journal, 2023, Vol 29, Issue 9, p1
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.202203162