C 2 group increment

Here is another instance of the extreme model dependency of strain energies in the fluorocarbon series. A strainless C(F)2(C)2 group increment of - 104.9 kcal mol" had earlier been derived ". In principle, one might expect that this increment would be applicable to calculating the strain energy of hexafluorocyclopropane. Applying this value, we concluded that the total strain in the molecule was 80.9 kcal mol" This was even higher than the value calculated by Bernett some years earlier 68.6 kcal mol" We were buoyed by the fact that the endothermicity of equation 18 indicated a strain of... 

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