Studies on Magnetic Properties of Transition Metal Polynuclear Complexes and Molecular Design Aiming to Single-Molecule Magnets

过渡金属多核配合物磁性能研究及单分子磁体分子设计

• 批准号: 14540533
• 负责人: NAKANO Motohiro
• 金额: $ 2.3万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540533/
• 关键词: single-molecule magnet; polynuclear complex; magnetic susceptibility; magnetic anisotropy; non-collinear magnetism; Spin-crossover complex; dielectric constant; Jahn-Teller effect

1.Relaxation Mechanism of Single-Chain MagnetsSingle-Chain Magnets (SCMs) are a class of quantum magnets, recently developed from Single-Molecule Magnets (SMMs). We proposed a novel mechanism of relaxation processes in SCMs based on a spin-vector model characterized by an intrachain ferromagnetic interaction J along with a single-ion anisotropy D. This model can be applied to a wide range of SCM systems from a SMM limit J/D 0 of isolated molecule to a Glauber-dynamics limit J/D >> 1 for a pure Ising chain. It is an excellent feature of the model that it provides a rational account for a "barrier-height crossover" observed in some ferromagnetic SCMs as a crossover of dominant relaxation process from a single-spin flip to a two-spin cluster flip possessing different activation barriers.2.Critical Phenomena of Spin-Crossover Complex [Mn(taa)]Spin-crossover complex [Mn(taa)] is known as a unique system showing a dielectric response in addition to an optically-controllable spin bistability. In order to clarify intermolecular interactions responsible to the phase transition in [Mn(taa)] crystals, we prepared some mixed-crystals with [Ga(taa)], a diamagnetic analogue of the Mn complex with the isomorphous crystal structure. A T-x phase diagram of [Mn_xGa_<1-x>(taa)] determined by magnetic and dielectric measurements revealed a critical phenomenon switching from a first-order phase transition to a spin-equilibrium behavior. The suppression of the spin-crossover phase transition made it possible to estimate the energy barrier for pseudo-rotation of an [Mn(taa)] molecule.3.Development of Computer Programs for Magnetization AnalysisSome computer codes were developed to analyze magnetization curves and HF-EPR results of SMMs. Among them a code implementing the ligand-field theoretical approach was especially effective to elucidate magnetic properties of SMMs including Co(II) ions, which were difficult to be treated by conventional spin-Hamiltonian approach.

1.单链磁体的弛豫机制单链磁体（SCM）是一类量子磁体，是最近从单分子磁体（SMM）发展而来的。我们提出了一种基于自旋矢量模型的 SCM 弛豫过程的新机制，该模型的特征是链内铁磁相互作用 J 和单离子各向异性 D。该模型可以从 SMM 极限 J 应用于广泛的 SCM 系统对于纯伊辛链，孤立分子的 /D 0 达到格劳伯动力学极限 J/D >> 1。该模型的一个出色特征是，它为在一些铁磁 SCM 中观察到的“势垒高度交叉”提供了合理的解释，即从单自旋翻转到具有不同激活的双自旋簇翻转的主导弛豫过程的交叉2.自旋交叉络合物[Mn(taa)]的关键现象自旋交叉络合物[Mn(taa)]被认为是一种独特的系统，除显示介电响应外，还显示介电响应光控自旋双稳态。为了阐明[Mn(taa)]晶体中导致相变的分子间相互作用，我们制备了一些与[Ga(taa)]的混合晶体，[Ga(taa)]是具有同晶晶体结构的Mn配合物的抗磁类似物。通过磁和介电测量确定的[Mn_xGa_<1-x>(taa)]的T-x相图揭示了从一级相变到自旋平衡行为的关键现象。自旋交叉相变的抑制使得估计[Mn(taa)]分子赝旋转的能垒成为可能。3.磁化分析计算机程序的开发开发了一些计算机代码来分析磁化曲线和HF -SMM 的 EPR 结果。其中，实现配体场理论方法的代码对于阐明包含 Co(II) 离子的 SMM 的磁性特别有效，而传统的自旋哈密尔顿方法很难处理这些磁性材料。

项目成果

M.Nakano et al.: "Dielectric behavior of manganese(III) spin-crossover complex [Mn(taa)]"Physical Review B. Vol.66. article no.212412 (2002)

M.Nakano 等人：“锰(III) 自旋交叉络合物 [Mn(taa)] 的介电行为”Physical Review B. Vol.66。

T.Hashiguchi et al.: "Heat capacities of quasi-two-dimensional hetero-spin honeycomb magnets {NBu_4[(CuCr^<III>)-Cr^<II>(ox)_3] }_n and { PPh_4[(MnCr^<III>)-Cr^<II>(ox)_3]}_n : High-temperature series expansion analysis"Journal of Chemical Physics. Vol.11

T.Hashiguchi 等人：“准二维异质自旋蜂窝磁体的热容量 {NBu_4[(CuCr^<III>)-Cr^<II>(ox)_3] }_n 和 { PPh_4[(MnCr)

M.Nakano et al.: "Dynamic Jahn-Teller character of mananese(III) spin-crossover complex [Mn(taa)] (H_3taa = tris(1-(2-azolyl)-2-azabuten-4-yl)amine)"ADVANCES IN QUANTUM CHEMISTRY. 44. 617-630 (2003)

M.Nakano 等人：“锰 (III) 自旋交叉复合物 [Mn(taa)] 的动态 Jahn-Teller 特征（H_3taa = 三（1-（2-唑基）-2-氮杂丁烯-4-基）胺）

K.Kubo et al.: "Oxidation of cobalt(III)-sulfur-rich dithiolate complexes and spectroscopic and electrical properties of the oxidized species"Inorganica Chimica Acta. Vol.346. 43-48 (2003)

K.Kubo 等人：“富含钴(III)-硫的二硫醇络合物的氧化以及氧化物质的光谱和电学性质”Inorganica Chimica Acta。

中野 元裕: "Dielectric behavior of manganese(III)spin-crossover complex[Mn(taa)]"Physical Review B. 66. 212412 (2003)

Motohiro Nakano：“锰(III)自旋交叉络合物的介电行为[Mn(taa)]”物理评论 B. 66. 212412 (2003)