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Impact of the α‐Ferrocenyl Group on the Solvolytic Reactivity – Electrofugality – of Ferrocenylphenylmethyl Cations
Author(s) -
Marijan Marijan,
Jurić Sandra,
Mihalić Zlatko,
Kronja Olga
Publication year - 2019
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.201801133
Subject(s) - chemistry , taft equation , moiety , reactivity (psychology) , ring (chemistry) , medicinal chemistry , reaction rate constant , stereochemistry , substituent , kinetics , organic chemistry , medicine , physics , alternative medicine , pathology , quantum mechanics
The electron‐donating effect of the ferrocenyl group in α‐position to the reaction center on S N 1 solvolytic reactivity has been quantified by determining the electrofugalities ( E f ) of a series of ferrocenyl‐X‐phenylmethyl cations according to the LFER equation: log k = s f ( E f + N f ). Due to highly stabilized transition state, the E f values are about eight units higher than those of the corresponding benzhydryl cations. Impact of the phenyl group in ferrocenylphenylmethyl derivatives on stabilization of the positive charge is somewhat leveled by the ferrocenyl group, so the rate effect of the substituents on the phenyl ring is suppressed, causing narrow range of E f parameters and small absolute values of the ρ + constant. Calculations at B2PLYP‐D3/may‐cc‐pVTZ level of theory showed that the positive charge in ferrocenylphenylmethyl cation is largely shifted from the phenyl to ferrocenyl moiety, and that the substituents on the phenyl ring have small impact on its stability.