13 C NMR of substituted aryl carbenium ions: Continuous dependence of the  ipso  substituent shifts upon the carbenium character. Use of proportionality relationships for the evaluation of substituent–substituent interactions | Zendy

Membrey François | Zendy; Ancian Bernard | Zendy; Doucet JeanPierre | Zendy

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13 C NMR of substituted aryl carbenium ions: Continuous dependence of the ipso substituent shifts upon the carbenium character. Use of proportionality relationships for the evaluation of substituent–substituent interactions

Author(s) -

Membrey François,

Ancian Bernard,

Doucet JeanPierre

Publication year - 1978

Publication title -

organic magnetic resonance

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.483

H-Index - 72

eISSN - 1097-458X

pISSN - 0030-4921

DOI - 10.1002/mrc.1270111111

Subject(s) - substituent , chemistry , carbenium ion , ion , additive function , chemical shift , aryl , stereochemistry , computational chemistry , crystallography , mathematics , organic chemistry , mathematical analysis , alkyl

13 C substituent shifts in para ‐substituted phenyl and 2‐phenylethenyl carbenium ions have been studied within the general model of para ‐disubstituted benzenes XC 6 H 4 Y. Large variations are observed for the ipso shifts induced by the Y substituents (Y = NO 2 . … OCH 3 ) depending upon the electron demand at the remote carbenium centre. A good representation of these substituent‐substituent interactions is obtained by a treatment derived from ‘proportionality relationships’, where the deviations from strict additivity are factorized into two terms characterizing, respectively, the influence of the fixed X group on the ring and the susceptibility of the incoming Y substituent. Continuity of the ipso shift variations in an extended range is demonstrated, without break‐off between neutral polarized systems or ions as the electronic influence of the fixed X group increases.

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