首页> 外文期刊>Chemistry: A European journal >One-Dimensional Ferromagnetically Coupled Bimetallic Chains Constructed with trans-[Ru(acac)(2)(CN)(2)](-): Syntheses, Structures, Magnetic Properties, and Density Functional Theoretical Study
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One-Dimensional Ferromagnetically Coupled Bimetallic Chains Constructed with trans-[Ru(acac)(2)(CN)(2)](-): Syntheses, Structures, Magnetic Properties, and Density Functional Theoretical Study

机译:反式[Ru(acac)(2)(CN)(2)](-)构成的一维铁磁耦合双金属链:合成,结构,磁性和密度泛函理论研究

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摘要

Four cyano-bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans-[Ru(acac)(2)(CN)(2)](-) (Hacac = acetylacetone): {[{Ni(tren)}-{Ru(acac)(2)(CN)(2)}][ClO4]center dot CH3OH}(n) (1) (tren = tris(2-aminoethyl)amine), {[{Ni(cyclen)}{Ru(acac)(2)(CN)(2)}][ClO4]center dot CH3OH}(n) (2) (cyclen = 1,4,7,10-tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)(2)(CN)(2)}]}(n) (3) (salen(2-) =N,N'-bis(salicylidene)-o-ethyldiamine dianion) and [{Mn(5,5'-Me(2)salen)}(2){Ru(acac)(2)(CN)(2)}][Ru(acac)(2)(CN)(2)]center dot 2CH(3)OH (4) (5,5'-Me(2)salen = N,N'-bis(5,5'-dimethylsalicylidene)-o-ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between Ni-II and R-III ions through cyano bridges with J = + 1.92 cm(-1), zJ' = 1.37 cm(-1), g = 2.20 for 1 and J = + 0.85 cm(-1), zJ' = -0.16 cm(-1), g = 2.24 for 2. Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J = + 0.62 cm(-1), zJ' = 0.09 cm(-1), g = 2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with T-N = 2.6 K. In compound 4, two Mn-III ions are coordinated to trans-[Ru(acac)(2)(CN)(2)](-) to form trinuclear Mn2Ru units, which are linked together by pi-pi stacking and weak Mn center dot center dot center dot O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0 K with phi = 0.25, characteristic of superparamagnetic behavior. The Mn-III center dot center dot center dot R-III coupling constant (through cyano bridges) and the coupling constant (between the trimers) are +0.87 and +0.24 cm(-1), respectively. Compound 4 is a novel single-chain magnet built from Mn2Ru trimers through non-covalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitals and the magnetic exchange interactions between Rum and M (M = Ni-II, Fe-III, and Me-III) ions. To explain the somewhat unexpected ferromagnetic coupling between low-spin Ru-III and high-spin Fe-III and Mn-III ions in compounds 3 and 4, respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitals may also be important in determining the overall magnetic coupling in these bimetallic assemblies.
机译:通过使用顺磁性构件反式-[Ru(acac)(2)(CN)(2)](-)(Hacac =乙酰丙酮)制备了四种氰基桥连的一维双金属聚合物:{[{Ni(tren)} -{Ru(acac)(2)(CN)(2)}] [ClO4]中心点CH3OH}(n)(1)(tren =三(2-氨基乙基)胺),{[{Ni(cycln)} {Ru(acac)(2)(CN)(2)}] [ClO4]中心点CH3OH}(n)(2)(周期数= 1,4,7,10-四氮杂环十二烷),{[{Fe(salen) } {Ru(acac)(2)(CN)(2)}]}(n)(3)(salen(2-)= N,N'-双(水杨基)-邻乙二胺二阴离子)和[{Mn (5,5'-Me(2)salen)}(2){Ru(acac)(2)(CN)(2)}] [Ru(acac)(2)(CN)(2)]中心点2CH (3)OH(4)(5,5'-Me(2)salen = N,N'-双(5,5'-二甲基水杨基)-o-乙二亚胺)。化合物1和2为1D锯齿状NiRu链,它们通过J = + 1.92 cm(-1),zJ'= 1.37 cm(-1),g = 2.20的氰基桥在Ni-II和R-III离子之间表现出铁磁耦合对于1和J = + 0.85 cm(-1),zJ'= -0.16 cm(-1),g = 2.24(对于2)。化合物3具有一维线性链结构,表现出链内铁磁耦合(J = + 0.62 cm( -1),zJ'= 0.09 cm(-1),g = 2.08),但在FeRu链之间发生反铁磁耦合,导致TN = 2.6 K的超磁行为。在化合物4中,两个Mn-III离子配位为反式-[Ru(acac)(2)(CN)(2)](-)形成三核Mn2Ru单元,这些单元通过pi-pi堆叠和弱Mn中心点中心点中心点中心点O *相互作用链接在一起,从而形成一维链。化合物4在φ= 0.25时显示低于3.0 K的慢磁弛豫,这是超顺磁行为的特征。 Mn-III中心点中心点中心点R-III耦合常数(通过氰基桥)和耦合常数(三聚体之间)分别为+0.87和+0.24 cm(-1)。化合物4是由Mn2Ru三聚体通过非共价相互作用构建的新型单链磁体。密度泛函理论(DFT)结合破碎对称状态方法用于计算分子磁轨道以及Rum与M(M = Ni-II,Fe-III和Me-III)离子之间的磁交换相互作用。为了解释化合物3和4中低自旋Ru-III离子与高自旋Fe-III和Mn-III离子之间有些出乎意料的铁磁耦合,建议除相对对称性外,磁的相对能量在确定这些双金属组件中的整体磁耦合时,轨道也可能很重要。

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