Transmission of polar substituent effects across the cubane ring system:19F substituent chemical shifts (SCS) of 4-substituted (X) cub-1-yl fluorides revisited

2009 ◽  
Vol 22 (11) ◽  
pp. 1065-1069 ◽  
Author(s):  
William Adcock
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Ring System ◽  
Polar Substituent

The additivity of substituent effects applied to angular methyl chemical shifts in the decalin ring system: The conformation of 10-methyl-cis-2-decalone

1965 ◽  
Vol 6 (37) ◽  
pp. 3267-3272 ◽  
Author(s):  
Kenneth L. Williamson ◽  
Thomas A. Spencer
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Ring System

An investigation into the origins of polar substituent effects upon 19F chemical shifts, using 4-substituted β,β-difluorostyrenes

1980 ◽  
Vol 58 (8) ◽  
pp. 839-845 ◽  
Author(s):  
William F. Reynolds ◽  
Victoria G. Gibb ◽  
Nick Plavac
Keyword(s):  
Chemical Shift ◽  
Electron Density ◽  
Molecular Orbital ◽  
Excellent Agreement ◽  
Field Effect ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Molecular Orbital Calculations ◽  
Chemical Shift Difference ◽  
Polar Substituent

19F, 13C, and 1H chemical shifts have been determined for β,β-difluorostyrene and eight 4-substituted derivatives. The β-fluorine chemical shift difference, ΔδF, is used to evaluate the constant in the Buckingham equation. A = 3.0 × 10−11 esu for C—F bonds which is in excellent agreement with the value derived by Adcock and Khor. This allows accurate estimates of direct field effect contributions to 19F chemical shifts in aryl fluorides. Substituent parameter correlations demonstrate that the primary polar effect on 19F chemical shifts is field-induced π polarization. Abinitio molecular orbital calculations confirm that the substituent-induced 19F chemical shifts reflect changes in fluorine π electron density.

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