Verbrückte und unverbrückte norbornyl-kationen in der gasphase. Berechnungen zur stabilität isomerer norbornyl-kationen mit hilfe quantenmechanischer verfahren

Reactions of an Intramolecular Frustrated Lewis Pair with Unsaturated Substrates: Evidence for a Concerted Olefin Addition Reaction

“…Let us assume the reaction would proceed in a stepwise manner; then, the addition of the boron Lewis acid part of 12 could lead to the reactive zwitterionic intermediate 22 (see Scheme ) . Sextet rearrangements in the norbornyl cation system are known to be fast. − Consequently, there would be a competition between internal capture (to form 23 ) and Wagner−Meerwein rearrangement to a new zwitterion ( 24 ). This again would face competition between internal nucleophilic capture (to form 25 ) and further rearrangement.…”

Steric Effects on Reaction Rates. VI. Application of a New MM2 Force‐Field for Carbenium Ions to Solvolysis Rates of Secondary p‐Toluenesulfonates

“…For MIND0/3 calculations the structure with C,, symmetry was imposed to he compatible with molecular mechanics. This structure does not correspond to a global minimum on the MIND0/3 energy surface [14]. [3]. '…”

Carbocations in Superacid Systems

“…Forsyth and Panyachotipun 898 observed large isotope shifts for the 13 C resonance at the cationic center of the deuteriated 2-methyl-2-norbornyl cation, which was attributed to the bridging structure. 902 Theoretical quantum mechanical calculations [903][904][905][906][907][908] have also been performed on the 2-norbornyl cation at various levels. Finally, the stability of a range of bridgehead cations including the 2-norbornyl cation has been determined by the FT-ICR method on dissociative proton attachment of bromides and alcohols.…”