“Free” [Fe(tpp)]+ Cation: A New Concept in the Search for the Least Coordinating Anion
✍ Scribed by Dr. Zuowei Xie; Prof. Robert Bau; Prof. Christopher A. Reed
- Book ID
- 101553259
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 254 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
✦ Synopsis
COMMUNICATIONS
the A ' state, the characteristic reaction of which is a very efficient f 1.71 hydrogen shift. This is in perfect agreement with the observation that though the optically prepared excited state of 4 depopulates within about 25 fs,["] ground-state 4 is produced only 26 ps after excitation.['21 It also confirms the model proposed to explain this dramatic difference of three orders of magnitude." 21 In addition, this is an indication that in spite of the limitations of semiempirical results as far as absolute accuracy is concerned, the energy difference of merely 0.4 kcalmol-obtained for the vertical excitation energies of 4 may be significant.
The excited-state acidic behavior observed for 1 might be due to the fact that the photoreactions observed for 4-6 are not operative in 1 because they are energetically unfavorable. since the intermediate cannot irreversibly rearomatize to a stable product.['31 This argument, however, is difficult to reconcile with the experimental observation that the [1,7] H shift occurs from a totally symmetric state and the fact that in 1 there is no low-lying state of this symmetry.
Further investigations into the structural and electronic prerequisites for excited-state carbon-acidic behavior are under way.