ORGN 90 |
| Oxidation of 5,10,15,20-tetramesitylporphyrin-iron(III) perchlorate with ferric perchlorate in acetonitrile gave the corresponding iron(IV) diperchlorate complex that relaxed rapidly to the iron(III) porphyrin radical cation (k = 0.07 s-1). This process was followed by UV-visible, EPR, and NMR spectroscopies. Irradiation of porphyrin-iron(IV) diperchlorate complex with 355 nm laser light gave a highly reactive transient tentatively identified as a porphyrin-iron(V)-oxo species. A similar method was applied to 5,10,15-tris(pentafluorophenyl)corrole-iron(IV) chlorate and nitrate complexes for formation of corrole-iron(V)-oxo species. The laser-generated iron(V)-oxo species have unique UV-visible spectra and exhibit reactivity that is 4-6 orders of magnitude greater than the corresponding iron(IV)-oxo macrocylic radical cations. Representative second-order rate constants for reactions with cis-cyclooctene in acetonitrile at 20 ± 2 °C are k = 1.3 × 105 M-1 s-1 for porphyrin-iron(V)-oxo species and k = 5900 M-1 s-1 for corrole-iron(V)-oxo species. |
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Process R&D, Physical Organic Chemistry, Heterocycles, Aromatics, Metal-Mediated Reactions
8:00 PM-10:00 PM, Sunday, March 25, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |