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Mixed-metal single-molecule magnets: Syntheses, structure, and magnetic properties of [Mn8Fe4O12(O2CR)16(H2O)4] (R = CH2Cl, CH2Br, CHCl2) |
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| Authors: | Chen-I Yang Shwu-Fen YangShao-Po Hung Gene-Hsiang LeeChing-Shuei Wur Hui-Lien Tsai |
| Institution: | a Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan b Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan c Instrumentation Center, College of Science, National Taiwan University, Taipei 106, Taiwan d Department of Physics, National Cheng Kung University, Tainan 701, Taiwan |
| Abstract: | Three mixed-metal single-molecule magnets containing Mn8Fe4O12]16+ cores are synthesized and characterized. The reaction of FeCl2·4H2O with KMnO4 and RCOOH (R = CH2Cl, CH2Br) in H2O gives Mn8Fe4O12(O2CR)16(H2O)4] (R = CH2Cl (1), CH2Br (2)) in yields of 43% and 40%, respectively. Treatment of complex 1 with an excess of CHCl2COOH in CH2Cl2 gives Mn8Fe4O12(O2CCHCl2)16(H2O)4]·CH2Cl2·10H2O (3·CH2Cl2·10H2O) in a yield of 83%. The X-ray structure analysis reveals that all three complexes consist of a trapped-valence dodecanuclear core comprising 4MnIII, 4FeIII, and 4MnIV ions. DC magnetic susceptibility and magnetization measurements indicate that all three complexes exhibit intramolecular antiferromagnetic interaction, resulting in an S = 4 ground state. In addition, frequency-dependent out-of-phase AC magnetic susceptibility signals at low temperature for complexes 1, 2, and 3 are indicative of their single-molecule magnetism behavior. |
| Keywords: | Mixed-metal complex Crystal structure Magnetoanisotropy Single-molecule magnetism Alternating current magnetic susceptibility |
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