Mn4 single-molecule magnets with a planar diamond core and S=9 |
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| Institution: | 1. Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0358, USA;2. Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA;3. Laboratoire Louis Néel, CNRS BP 166, Avenue des Martyrs, 38042 Grenoble Cedex 9, France;4. Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA;5. Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK;1. Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, PR China;2. Department of Material and Chemical Engineering, Chizhou University, Chizhou, Anhui 247000, PR China;1. College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China;2. Central Laboratory, Fuzhou University, Fuzhou 350002, China;1. Institute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia;2. Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141 980 Dubna, Moscow Region, Russian Federation |
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| Abstract: | The syntheses and magnetic properties are reported for three Mn4 single-molecule magnets (SMMs): Mn4(hmp)6(NO3)2(MeCN)2](ClO4)2·2MeCN (3), Mn4(hmp)6(NO3)4]·(MeCN) (4), and Mn4(hmp)4(acac)2(MeO)2](ClO4)2·2MeOH (5). In each complex there is a planar diamond core of MnIII 2MnII 2 ions. An analysis of the variable-temperature and variable-field magnetization data indicate that all three molecules have intramolecular ferromagnetic coupling and a S=9 ground state. The presence of a frequency-dependent alternating current susceptibility signal indicates a significant energy barrier between the spin-up and spin-down states for each of these three MnIII 2MnII 2 complexes. The fact that these complexes are SMMs has been confirmed by the observation of hysteresis in the plot of magnetization versus magnetic field measured for single crystals of complexes 3 and 4. The hysteresis loops for both of these complexes exhibit steps characteristic of quantum tunneling of magnetization. Complex 4 shows its first step at zero field, whereas the first step for complex 3 is shifted to −0.10 T. This shift is attributable to weak intermolecular antiferromagnetic exchange interactions present for complex 3. |
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