Crystal packing effects within [Mn III 3O] 7+ single-molecule magnets: Controlling intermolecular antiferromagnetic interactions

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Title:	Crystal packing effects within [Mn III 3O] 7+ single-molecule magnets: Controlling intermolecular antiferromagnetic interactions
Authors:	Yang, C.-I.ab, Cheng, K.-H.a, Hung, S.-P.a, Nakano, M.c, Tsai, H.-L.a
Contributors:	Department of Chemistry, Tunghai University
Keywords:	Magnetic anisotropy;Nanoscale magnet;Single-molecule magnet;Superparamagnet;Trinuclear manganese complex
Date:	2011
Issue Date:	2013-05-14T09:02:40Z (UTC)
Abstract:	The reactions of 2-hydroxyphenylethanone oxime (Me-H 2salox) and (2-hydroxy-phenyl)-phenyl-methanone oxime (Ph-H 2salox) with Mn(ClO 4) 2?6H 2O in MeOH afford trinuclear manganese complexes of [Mn 3O(Me-salox) 3(MeOH) 3(ClO 4)]?MeOH (1?MeOH) and [Mn 3O(Ph-salox) 3(MeOH) 3(ClO 4)] ?2MeOH (2?2MeOH), respectively. X-ray analysis shows that both complexes contain a manganese triangle core, [Mn III 3O] 7+. The structural distortion from the twisting of the oxime ligands dominates the ferromagnetic interactions within the three Mn ions in both compounds and results in an S = 6 ground state. The frequency dependence of out-of-phase signals in the alternating current (AC) magnetic susceptibility measurements and the temperature-dependent and sweep-rate-dependent hysteresis loops are indicative of single-molecule magnet behavior. Moreover, both complexes show step-wise magnetization, indicating the occurrence of quantum tunneling of magnetization (QTM). Interestingly, a tail to tail arrangement in the crystal packing of complex 1?MeOH results in strong intermolecular H-bonding interactions and leads to the exchange-bias effect from the antiferromagnetic interaction between the adjacent Mn 3 molecules. In contract, QTM steps of complex 2?2MeOH show an absence of the exchange-bias effect due to a weak intermolecular interaction from a head to tail arrangement. ? 2011 Elsevier B.V. All rights reserved.
Relation:	Polyhedron Volume 30, Issue 18, 28 November 2011, Pages 3272-3278
Appears in Collections:	[化學系所] 期刊論文

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