Magnetic Interactions in Dinuclear MnMn Complexes Covalently Tethered to Organic Radicals: Spectroscopic Models for the SY· State of Photosystem II.
A series of isostructural dimeric manganese complexes of the type [(Medtne)Mn(u-O)(μ- R)](X) have been prepared and characterized. The dimanganese cores of these complexes are rigidly held together by the hexadentate ligand Medtne (Medtne = 1 ,2-bis(4,7-dimethyl-1 ,4,7-triazacyclonon-1- yl)ethane)....
| Publicado en: | Journal of the American Chemical Society Vol. 127; no. 16; pp. 6095 - 6109 |
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| Autores principales: | , , , , |
| Formato: | Artículo |
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American Chemical Society
4/27/2005
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=16924276&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 16924276 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 4/27/2005 vid: 127 iid: 16 pid: 997 pub: American Chemical Society artinfo: ui: 16924276 10.1021/ja042655w ppf: 6095 ppct: 14 formats: tig: atl: Magnetic Interactions in Dinuclear MnMn Complexes Covalently Tethered to Organic Radicals: Spectroscopic Models for the SY· State of Photosystem II. aug: au: Marlin, Dana S. Bill, Eckhard Weyhermüller, Thomas Bothe, Eberhard Wieghardt, Karl affil: School of Chemistry, The University of Edinburgh, Edinburgh, Scotland. Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Müiheim an der Ruhr, Germany. su: Chemical reactions Radicals (Chemistry) Magnesium Complex compounds Ligands (Chemistry) Optical diffraction Molecular structure sug: subj: Chemical reactions Radicals (Chemistry) Magnesium Complex compounds Ligands (Chemistry) Optical diffraction Molecular structure ab: A series of isostructural dimeric manganese complexes of the type [(Medtne)Mn(u-O)(μ- R)](X) have been prepared and characterized. The dimanganese cores of these complexes are rigidly held together by the hexadentate ligand Medtne (Medtne = 1 ,2-bis(4,7-dimethyl-1 ,4,7-triazacyclonon-1- yl)ethane). Molecular structures for the entire series have been obtained by X-ray diffraction measurements, of which complexes 2 (R = OBPh), 3 (R = OC-PROXVL), 4 (B = OC-TEMPO), and 5 (R = OBPhNIT) are reported here (HOC-PROXYL = 3-carboxy-2,2,5,5-tetramethylpyrrolidin-1 -yloxy; HOC-TEMPO = 4-carboxy-2,2,6,6-tetramethylpiperidin-1-yloxy; and HOBPhNIT = 2-(4-(dihydroxyboranyl)- phenyl)-4,4,5,5-tetramethyl-3-oxyimidazolidin-1-oxide). The structures of 1 (R = OAc) and 6 (R = OCPhNIT) have been reported previously (HOCPhNIT = 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-3- oxyimidazolidin-1-oxide). All complexes exhibit several redox states, which have been investigated by electrochemistry. Complexes 1, 3, 4, and 6 contain a mixed-valent MnMn core with an isolated magnetic ground state of S = 1/2. The exchange coupling between the manganese ions is strong throughout the series (J ≈ -130 ± 10 cm, H= -2JSS). The radical complexes 3,4, and 6 exhibit, in addition, long- range exchange interaction (6.9, 7.7, and 8.8 Å, respectively) between the organic radical and the dimanganese core. The intramolecular anisotropic coupling was determined from cw-EPR line shape analyses at S-, X-, and Q-band frequencies and from the intensity of half-field signals detected in normal- and parallel-mode (J= -120 × 10, -105 × 10, and -140 × 10 cm, for 3,4, and 6 respectively). Distance information was obtained for the dimanganese core and the organic radicals from these values by using a three-spin dipole model and local spin contributions for the manganese ions. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2005 holdings: @attributes: islocal: N |
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