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The 1‐Phenyl‐1‐(trimethylsilyl)ethyl Cation: An NMR Spectroscopic and Computational Study of the α‐Silyl Effect in Benzyl Cations
Author(s) -
Kostenko Arseni,
Müller Bernhard,
Kaufmann FrankPeter,
Apeloig Yitzhak,
Siehl HansUllrich
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201101741
Subject(s) - chemistry , silylation , trimethylsilyl , substituent , chemical shift , nuclear magnetic resonance spectroscopy , spectroscopy , aromaticity , quantum chemical , computational chemistry , medicinal chemistry , organic chemistry , molecule , catalysis , physics , quantum mechanics
The 1‐phenyl‐1‐(trimethylsilyl)ethyl cation is generated as a persistent species in solution and characterized experimentally by 1 H, 13 C, and 29 Si NMR spectroscopy. The α‐silyl effect is elucidated by comparison with other benzyl cations, such as cumyl and 1‐phenylethyl cations. Concomitant quantum chemical calculations of structures, relative thermodynamic stabilities, chemical shifts, and the harmonic oscillator model of aromaticity (HOMA) indices are congruent with the analysis of the experimental NMR spectroscopy results; therefore, we conclude that, in benzyl cations, the α‐silyl substituent is stabilizing with respect to H, but destabilizing relative to a methyl group.