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{| class="collapsible collapsed wikitable"
 
{| class="collapsible collapsed wikitable"
 
|-
 
|-
!'''Twisted geometry'''
+
!'''Twisted (perpendicular) geometry'''
 
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|-
 
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  $BLWDAT
 
  $BLWDAT
 
   2 8 0
 
   2 8 0
    4 8 13 15 38 42 47 49
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  3  7 13 14 18 22 28 29
 
   2 8 0
 
   2 8 0
  18 22 28 29 52 56 62 63
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34 38 43 45 49 53 58 60
26 56 -1
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  26 56 -1
$END
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$END
  
 
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Version du 11 juillet 2012 à 16:50

return to Tutorial n°4 Two geometries are provided the planar and the twisted where a vinyl part C1 C5 has been twisted by 90°. this second moieties has its pi orbitals along the y direction.

Evaluation of the conjugaison

Localization of px-like pi orbitals to deconjugate keeping planar

Evaluation of the hyperconjugaison in the twisted form

In the BLW part we localize px-like pi orbitals of atoms C2 and C6 and py-like orbitals for C1 C5 to avoid hyperconjugaison.

We find
delocalized planar -155.8824504889
localized planar -155.8603462862 (13.9 kcal/mol)
Twisted -155.8695790387 ( 8.1 kcal/mol)
Twisted but local -155.8537320442 (18.0 kcal/mol)

Hence conjugaison is 13.9 kcal/mol, and the hyper conjugaison in the twisted form is as large as 9.9 kcal/mol