Trimethylenemethane radical anions

Intra-complex TMS+ abstraction by F yields the trimethylenemethane radical anion 33. Similarly, a number of other (mostly aromatic) distonic radical anions have been generated. Using the same approach, several other highly unsaturated distonic negative ions, such as the benzyne radical anions, were also studied164. 

It is obvious that the isobutene unit provides a good starting point for the generation of trimethylenemethane radical anions. However, even isobutane units can be used to produce these more highly unsaturated species. In a preliminary work aimed at two-and three-fold deprotonation processes in solution, Kuck, de Meijere and coworkers165 have subjected triquinacene (41) and the tribenzotriquinacenes 44 to NCI conditions with... 

CH4/O2 and CF4 as the reactant gases and observed the formation of [M — 4 H] ions in the Cl plasma (Scheme 13)166. Thus, repeated deprotonation and electron transfer processes appear to offer an efficient access to more highly unsaturated and/or ring condensed trimethylenemethane radical anions. The [M — 4 H]- ion is considered identical to the molecular radical anion (42) of acepentalene (43), which was generated as a short-lived species from the former by neutralization-reionization mass spectrometry167. Efforts to apply Squires methodology to triquinacene 41 and the tribenzotriquinacenes 44 have been made168. 

Also to be mentioned are the reactions of oxygen atom radical anions with organic substrates. These reactions were reviewed by Gronert (2001). For the reactivity of the atomic oxygen anion-radical, see Section 1.7.2. The atomic oxygen anion-radical reacts with benzene, tetramethylene ethane, or cyclopentadienylidene trimethylenemethane. The reactions consist in abstraction of H2 with the formation of H2O and the corresponding distonic anion-radicals as products. 

Calculations have been carried out on the spectroscopy and excited-state energies and geometries of polyenes,84 the 1,5-cyclo-octadiyne radical cation,85 the visual chromophore, ll-c/s-retinal,8 polyene carbaldehydes,87 aromatic hydrocarbon anions and cations,88 trimethylenemethane,89 thiamine derivatives,80 porphyrins,91 lumiflavin,92 chlorophyll,93 nucleic acids,94 and ferrocene.95... 

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