An unusal case of facile non-degenerate P-C bond making and breaking
| Autor: | Asli Cangönül, Lili Shi, Frank Neese, Aysel Özbolat‐Schön, Vitaly Nesterov, Gregor Schnakenburg, Maurice van Gastel, Rainer Streubel |
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| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Atropisomer Free Radicals Chemistry Ligand Stereochemistry Phosphines Radical Organic Chemistry Electron Spin Resonance Spectroscopy Electrons General Chemistry Lithium Crystallography X-Ray Biochemistry Tautomer law.invention Crystallography Deprotonation Isomerism law Singlet state Electron paramagnetic resonance Oxidation-Reduction Bond cleavage |
| Zdroj: | Chemistry, an Asian journal. 7(7) |
| ISSN: | 1861-471X |
| Popis: | Oxidation of Li/X phosphinidenoid complex 2, obtained via selective deprotonation from the P-H precursor 1, with [Ph(3)C]BF(4) led to the formation of two P-F substituted diorganophosphane complexes 6,7; the latter tautomer 7 formed via H-shift from 6. In contrast, oxidation of 2 with [(p-Tol)(3)C]BF(4) led to three major and one minor intermediates at low temperature, which we tentatively assign to two pairs of P-C atropisomers 10 a,a' and 10 c,c' and which differ by the relative orientations of their CH(SiMe(3))(2) and W(CO)(5) groups. Conversion of all isomers led finally to complex 11 having a ligand with a long P-C bond to the central trityl* carbon atom, firmly established by single-crystal X-ray analysis. DFT calculations at the B3LYP/def2-TZVPP//BP86/def2-TZVP level of theory on real molecular entities revealed the structures of the in situ formed combined singlet diradicals (4+5 and 5+9) and the nature of intermediates on the way to the final product, complex 11. Remarkable is that all isomers of 11 possess relative energies in the narrow energy regime of about 20 kcal mol(-1). A preliminary study revealed that complex 11 undergoes selective P-C bond cleavage at 75 °C in toluene solution. |
| Databáze: | OpenAIRE |
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