Ni Zhong-Hai, Tao Jun, Wernsdorfer Wolfgang, Cui Ai-Li, Kou Hui-Zhong
Department of Chemistry, Tsinghua University, Beijing, 100084, PR China.
Dalton Trans. 2009 Apr 21(15):2788-94. doi: 10.1039/b814860k. Epub 2009 Feb 23.
The reaction of trans-[Fe(R-bpb)(CN)2]- (R-bpb2-=R-substituted-1,2-bis(pyridine-2-carboxamido)benzenate) with trans-Mn(III) Schiff base complexes [Mn(5-X-saltn)]ClO4 (5-X-saltn2-=N,N'-propanolbis(5-X-substituted-salcylideneiminato) dianion) gave rise to cyanide-bridged neutral binuclear [MnFe] compounds [Mn(saltn)(MeOH)][Fe(bpb)(CN)2].3H2O (), [Mn(saltn)(H2O)Fe(bpmb)(CN)2].H2O (), [Mn(saltn)(MeOH)Fe(bpClb)(CN)2].2H2O (), and ionic [Mn2Fe]+-[Fe]- complexes [Mn2(5-Br-saltn)2(H2O)(EtOH)Fe(bpb)(CN)2][Fe(bpb)(CN)2].6H2O () and [Mn2(5-Cl-saltn)2(CH3OH)(EtOH)Fe(bpb)(CN)2][Fe(bpb)(CN)2].5H2O.MeCN (). Four binuclear units of complexes assemble in a head-to-tail way via hydrogen bonding giving rise to a metallo-supramolecular [MnFe]4 square, while two [Mn2Fe]+-[Fe]- units of complexes form a metallo-supramolecular macrocyclic structure. Magnetic studies reveal that complexes and exhibit intermetallic ferromagnetic coupling, while complex displays antiferromagnetic interaction between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridges. Complexes , and display frequency dependent of current-alternating (ac) magnetic susceptibility, typical of the presence of slow magnetization relaxation. Because of the existence of intermolecular magnetic interaction, complex shows an exchange-biased single-molecule magnet (SMM) behavior below 0.5 K.
反式-[Fe(R-bpb)(CN)₂]⁻（R-bpb²⁻ = R-取代的-1,2-双（吡啶-2-甲酰胺基）苯甲酸根）与反式-Mn(III)席夫碱配合物[Mn(5-X-saltn)]ClO₄（5-X-saltn²⁻ = N,N'-丙醇双（5-X-取代-水杨醛亚胺基）二价阴离子）反应生成了氰基桥连的中性双核[MnFe]化合物[Mn(saltn)(MeOH)][Fe(bpb)(CN)₂]·3H₂O（）、[Mn(saltn)(H₂O)Fe(bpmb)(CN)₂]·H₂O（）、[Mn(saltn)(MeOH)Fe(bpClb)(CN)₂]·2H₂O（）以及离子型[Mn₂Fe]⁺-[Fe]⁻配合物[Mn₂(5-Br-saltn)₂(H₂O)(EtOH)Fe(bpb)(CN)₂][Fe(bpb)(CN)₂]·6H₂O（）和[Mn₂(5-Cl-saltn)₂(CH₃OH)(EtOH)Fe(bpb)(CN)₂][Fe(bpb)(CN)₂]·5H₂O·MeCN（）。配合物的四个双核单元通过氢键以头对尾的方式组装，形成了一个金属超分子[MnFe]₄正方形，而配合物的两个[Mn₂Fe]⁺-[Fe]⁻单元形成了一个金属超分子大环结构。磁性研究表明，配合物和表现出金属间铁磁耦合，而配合物通过氰基桥在低自旋Fe(III)和高自旋Mn(III)之间表现出反铁磁相互作用。配合物、和表现出与电流交变（ac）磁化率相关的频率依赖性，这是慢磁化弛豫存在的典型特征。由于分子间磁相互作用的存在，配合物在0.5 K以下表现出交换偏置的单分子磁体（SMM）行为。
