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Hydrogencyanamide-bridged one-dimensional polymers built on Mn-II-Schiff base fragments: Synthesis, structure, and magnetism

机译:基于Mn-II-席夫碱基片段的水力酰胺桥联的一维聚合物:合成,结构和磁性

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The ability of NCNH- to construct transition metal coordination polymers and to transmit magnetic coupling was investigated. By introduction of various tetradentate Schiff base ligands (L) and different solvents (S), nine NCNH--bridged manganese(III) coordination complexes were obtained. Their structures can be divided into three types: I) NCNH-bridged chains built on mononuclear [Mn-III (L)] units, [Mn-III (L)(mu(1,3)-NCNH)(n) (L=5-Brsalen (1), 5-Clsalen (2)); II)NCNH-bridged chains built on dinuclear [Mn-III (2)(L)(2)] units, complexes 3-8, [Mn-III (2)(L)(2)(mu(1,3)-NCNH)]ClO4 center dot S (L=salen, 5-Fsalen, 5-Clsalen, 5-OCH(3)salen; S=CH3OH or C2H5OH); III) NCNH-bridged Mn-III dimers linked by hydrogen bonds into a 1D polymer, {[Mn-III (3-OCH(3)salen)-(H2O)](2)(mu(1,3)-NCNH)}ClO4 center dot 0.5H(2)O, salen=N,N'-bis(salicylidene)-1,2-diaminoethane). In these complexes, the N equivalent to C-NH- resonance structure dominates the bonding mode of the NCNH- ligand adopting the mu(1,3)-bridging mode. Magnetic characterization shows that the asymmetric NCNH- bridge transmits antiferromagnetic interaction between Mn-III ions and often favors the weak ferromagnetism caused by spin canting in these one-dimensional chains. However, these complexes exhibit different magnetic behaviors at low temperatures.
机译:研究了NCNH-构造过渡金属配位聚合物和传输磁耦合的能力。通过引入各种四齿席夫碱配体(L)和不同溶剂(S),获得了九种NCNH-桥联锰(III)配位络合物。它们的结构可以分为三种类型:I)基于单核[Mn-III(L)]单元,[Mn-III(L)(mu(1,3)-NCNH)(n)(L)的NCNH桥链= 5-Brsalen(1),5-Clsalen(2)); II)在双核[Mn-III(2)(L)(2)]单元,配合物3-8,[Mn-III(2)(L)(2)(mu(1,3))上构建的NCNH桥链-NCNH)] ClO4中心点S(L = salen,5-Fsalen,5-Clsalen,5-OCH(3)salen; S = CH3OH或C2H5OH); III)NCNH桥接的Mn-III二聚体通过氢键连接成一维聚合物,{[Mn-III(3-OCH(3)salen)-(H2O)](2)(mu(1,3)-NCNH) } ClO4中心点0.5H(2)O,salen = N,N'-双(水杨基)-1,2-二氨基乙烷)。在这些配合物中,相当于C-NH-共振结构的N决定了采用mu(1,3)-桥接模式的NCNH-配体的键合模式。磁性表征表明,不对称的NCNH-桥传递Mn-III离子之间的反铁磁相互作用,并且通常有利于这些一维链中自旋倾斜引起的弱铁磁。但是,这些配合物在低温下表现出不同的磁行为。

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