Cubyl cation

Applications of Electronic Structure Calculations to Explaining and Predicting the Chemistry of Three Reactive Intermediates—Phenylnitrene, Cubyl Cation,... 

Section 4 discusses the apphcation of electronic structure calculations to understanding and predicting the outcome of experiments on three different types of Rl. The examples in this section are taken from research, performed in collaborations between the author s group and the groups of experimentalists. The three RIs discussed in Section 4 are phenyinitrene, cubyl cation, and propane-1,3-diyls. 

APPLICATIONS OF ELECTRONIC STRUCTURE CALCULATIONS TO EXPLAINING AND PREDICTING THE CHEMISTRY OF THREE REACTIVE INTERMEDIATES—PHENYLNITRENE, CUBYL CATION, AND PROPANE-1,3-DIYL... 

Figure 22.5. The MP2/6-31G bond lengths and net Mulliken charges (in italics) at C—H groups, computed for cubyl cation 4. Resonance structures A and B are consistent with the calculated bond lengths and charges whereas, structure C is not.

For many polycyclic carbocations there is a good correlation between the changes in strain energies on carbocation formation, predicted by molecular mechanics calculations, and the solvolysis rates. However, at 70° cubyl cation is formed 10 times faster than expected from this correlation." " " What is responsible for this huge rate acceleration ... 

Photolysis of 1,4-diiodocubane (494) in nucleophilic solvents, such as methanol, was found to provide effectively the substitution product 495 (Scheme 6.241).1348 It was argued that the reaction proceeds via the formation of a caged radical pair and electron transfer to give iodide ion and a carbocation, which is trapped by the solvent (SN1 pathway). Hyperconjugative stabilization in cubyl cation cannot assist much from an extremely strained olefin cubene. However, the authors expected that photochemical fission of the C—I bond would still provide sufficient energy for production of the cation intermediate. 

The dominant mode of this interaction, like that in cubyl cation, involves bonding interactions with the distal, rather than the proximal carbons in the four-membered rings. This type of interaction in 1,4-dehydrocubane is illustrated by the... 

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