- Resonanzstabilisierung von Alkylradikalen durch zwei geminale Cyangruppen
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Effects of Substituents on the Strength of C-C bonds, 10. - Resonance Stabilization of Alkyl Radicals by Two Geminal Cyano groups The activation parameters of the homolytic cleavage of the Cq-Cq bonds of several dialkylated malonodinitriles (2-5) and of 1,1,2,2-tetracyanoethane (7) and the heat of dissociation of 6 in solution have been determined.Together with the ground state strain of the radical precursor (obtained from the heats of combustion or EFF calculations) the steric influence on the dissociation process has been determined.The resonancestabilization energy of α,α'-dicyanoalkyl radicals then calculated was (12.4 +/- 0.9) kcal/mol.This result is discussed within the concept of capto-dative stabilization.The destabilizing interaction of two geminal cyano groups is apparently the same in the ground state of 2-7 and the radicals generated from them.
- Pakusch, Joachim,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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p. 1191 - 1198
(2007/10/02)
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- Unusual Rearrangements in Di-?-methane Systems: Mechanistic and Exploratory Organic Photochemistry
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The triplet photochemistry of 1,1-dicyano-5,5-diphenyl-3,3-diisopropyl-1,4-pentadiene was investigated to determine if the high reactivity of di-?-methane systems with central diphenyl substitution derived from electronic or from steric effects.Sensitized
- Zimmerman, Howard E.,Cassel, Jonathan M.
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p. 3800 - 3816
(2007/10/02)
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