Reactions Involving Carbenes, Nitrenes, and Other Electron-Deficient Intermediates

Reactions Involving Carbenes, Nitrenes, and Other Electron-Deficient Intermediates 

The reactions to be described in this chapter have in common the formal involvement of even-electron intermediates having unfilled orbitals of low energy. The most familiar of these intermediates are carbonium ions. Sections 8.4 and 8.5 contain examples of fragmentation and rearrangement reactions of carbonium ions that are of synthetic value the discussion of these reactions supplements the mechanistically oriented discussion presented in Part A, Chapter 5. Also important are the neutral divalent carbon and monovalent nitrogen species, carbenes and nitrenes, respectively. 

CHAPTER 8 REACTIONS INVOLVING ELECTRON-DEFICIENT INTERMEDIATES 

Moreover, some of the reactions to be discussed have been clearly shown not to involve free carbenes or nitrenes, but are included here because the reactivity pattern is closely analogous. 

A carbene may exist in its ground electronic state as a singlet or a triplet, depending on whether the two nonbonded electrons are, respectively, in the same molecular orbital with paired spins, or in two orbitals of equal energy with parallel spins. 

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