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http://140.128.103.80:8080/handle/310901/21182
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Title: | Mixed-valence tetra- and hexanuclear manganese complexes from the flexibility of pyridine-containing β-diketone ligands |
Authors: | Yang, C.-I.a, Wernsdorfer, W.b, Tsai, Y.-J.a, Chung, G.a, Kuo, T.-S.c, Lee, G.-H.d, Shieh, M.c, Tsai, H.-L.a |
Contributors: | Department of Chemistry, Tunghai University |
Date: | 2008 |
Issue Date: | 2013-05-14T09:03:01Z (UTC)
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Abstract: | The reactions of [Mn 3O(O 2CCCl 3) 6(H 2O) 3] with 1-phenyl-3-(2-pyridyl)propane-1, 3-dione (HL 1) and 1-(2-pyridly)-3-(p-tolyl)propane-1,3-dione (HL 2) in CH 2Cl 2 afford the mixed-valence Mn II 2Mn III 2 tetranuclear complexes [Mn 4O-(O 2CCCl 3) 6(L 1) 2] (1) and [Mn 4O(O 2CCCl 3) 6L 2 2] (2), respectively. Similar reactions employing [Mn 3O(O 2CPh) 6(H 2O)(py) 2] with HL 1 and HL 2 give the Mn II 3Mn III 3 hexanuclear complexes [Mn 6O 2(O 2CPh) 8(L 1) 3] (3) and [Mn 6O 2(O 2CPh) 8L 3 2] (4), respectively. Complexes 1·2CH 2Cl 2, 2·2CH 2Cl 2·H 2O, 3·1.5CH 2Cl 2·Et 2O·H 2O, and 4·2CH 2Cl 2 crystallize in the triclinic space group P1, monoclinic space group P2 1/c, monoclinic space group P2 1/n, and monoclinic space group P2 1/n, respectively. Complexes 1 and 2 consist of a trapped-valence tetranuclear core of [Mn II 2Mn III 2(μ 4-0)] 8+, and complexes 3 and 4 represent a new structural type, possessing a [Mn II 3Mn III 3(μ 4-O) 2] 11+ core. The magnetic data indicate that complexes 3 and 4 have a ground-state spin value of S = 7/2 with significant magnetoanisotropy as gauged by the D values of -0.51 cm -1 and -0.46 cm -1, respectively, and frequency-dependent out-of-phase signals in alternating current magnetic susceptibility studies indicate their superparamagnetic behavior. In contrast, complexes 1 and 2 are low-spin molecules with an S = 1 ground state. Single-molecule magnetism behavior confirmed for 3 the presence of sweep-rate and temperature-dependent hysteresis loops in single-crystal M versus H studies at temperatures down to 40 mK. ? 2008 American Chemical Society. |
Relation: | Inorganic Chemistry Volume 47, Issue 6, 17 March 2008, Pages 1925-1939 |
Appears in Collections: | [化學系所] 期刊論文
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