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Document Type |
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Article In Journal |
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Document Title |
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Oxidation of tetranuclear copper(I) complexes [(Pip)nCuX]4; n = 1 or 2, Pip = piperidine and X = Cl or Br, with two equivalents of tetrachloro-1,2-benzoquinone (TClBQ) and sequentional oxidation with one equivalent of TClBQ followed by dioxygen in aprotic Oxidation of tetranuclear copper(I) complexes [(Pip)nCuX]4; n = 1 or 2, Pip = piperidine and X = Cl or Br, with two equivalents of tetrachloro-1,2-benzoquinone (TClBQ) and sequentional oxidation with one equivalent of TClBQ followed by dioxygen in aprotic |
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Subject |
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Oxidation of tetranuclear copper(I) complexes [(Pip)nCuX]4; n = 1 or 2, Pip = piperidine and X = Cl or Br, with two equivalents of tetrachloro-1,2-benzoquinone (TClBQ) and sequentional oxidation with one equivalent of TClBQ followed by dioxygen in aprotic |
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Document Language |
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English |
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Abstract |
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Copper(I) halides react quantitatively with piperidine in dioxygen-free CH2Cl2 or PhNO2 to form tetranuclear copper(I) complexes [(pip)nCuX]4; n = 1 or 2 and X = Cl or Br. These complexes are very soluble in CH2Cl2and PhNO2 and completely reduce tetrachlorol,2-benzoquinone (TClBQ) and O2 to the 3,4,5,6-tetrachlorocatecholato ligand (Cat) and the oxo form. The stable solid complexes [(pip)nCuX]4Cat2 and [(pip)nCuX]4CatO are closely related to the intermediate, bridging μ-catecholato complex, which is formed during the mono-oxygenation and oxidation of PhOH by oxytyrosinase. Cryoscopic and analytical data for these complexes indicate that [(pip)nCuX]4Cat2 and [(pip)nCuX]4CatO are discrete tetranuclear species. Electronic transition spectra in the near i.r. with high molecular absorptivity are diagnostic for a tetranuclear 'Cu4X4' core structure. The electronic transitions are more likely to be due to charge transfer between a minimum of three halo ligands to the copper(II) center. The room temperature e.p.r. spectra of [(pip)nCuX]4Cat2 and [(pip)nCuX]4CatO in CH2Cl2are isotropic with four hyperfine lines. The room temperature solid state e.p.r. spectra of these complexes show an axial spectra with dx2-y2 ground state, suggesting a square pyramidal arrangement around copper(II) centers in all n = 1 complexes and an elongated tetragonal octahedral arrangement around copper(II) centers in all n = 2 complexes. Cyclic voltammetry measurements show that they are more likely to be irreversible and show slight quasi-reversibility when X = Br and n = 2. Constant potential electrolysis indicate that the number of electrons consumed are equal to four which will be due to the reduction of four copper(II) species to copper(I). |
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ISSN |
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0340-4285 |
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Journal Name |
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Transition metal chemistry |
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Volume |
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30 |
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Issue Number |
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5 |
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Publishing Year |
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1426 AH
2005 AD |
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Number Of Pages |
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7 |
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Article Type |
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Article |
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Added Date |
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Thursday, July 2, 2009 |
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Researchers
| Mohamed A. | Mohamed A. | Investigator | Doctorate | |
| Ahmed H. | Ahmed H. | Researcher | Doctorate | |
| Tahani A. | Tahani A. | Researcher | Doctorate | |
| Ali | Ali | Researcher | Doctorate | |
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