论文总字数：21486字

摘 要

分子基磁性材料具有丰富的物理、化学性质，在催化、光学、磁学及导电材料等领域都有广泛应用，具有广阔的发展前景。过渡金属二硫烯配合物由于离域化的共轭体系常用作分子磁体，由于其特殊的导电、磁学及非线性光学等性质，近年备受关注。

在工作中，我们合成了一种新型的金属二硫烯配合物(BrBnMeIm)Ni(mnt)₂，通过溶剂挥发法得到单晶并表征了该化合物的晶体结构，并且借助热重、DSC及磁化率测试等分析手段，对它的热稳定性及磁性进行了探究。(BrBnMeIm)Ni(mnt)₂属于三斜晶系，空间群为P-1，[Ni(mnt)₂]^-阴离子和BrBnMeIm 阳离子形成交替层状堆积。在阴离子堆积柱中，阴离子面对面堆积，可能存在自旋二聚交换。在X-射线粉末衍射谱中，(BrBnMeIm)Ni(mnt)₂粉末的衍射峰与其单晶结构模拟PXRD峰的衍射峰位置基本一致，表明所得晶体具有很高的相纯度。在TGA测定中，通过热重曲线可知在室温至566 K，(BrBnMeIm)Ni(mnt)₂化合物无明显失重，表明其具有良好的热稳定性。在磁化率测定中，摩尔磁化率图显示，0-400 K范围内存在磁异常，转变温度为243 K与DSC测试(239 K时出现一个微小热响应吸热峰)中的相变点接近但并不完全一致，但我们尚未有足够的证据证明此处发生结构相变。

关键词：[Ni(mnt)₂]^n- 磁性质 结构相变 晶体结构

ABSTRACT

Molecular-based magnetic materials have rich physical and chemical properties, are widely used in the fields of catalysis, optics, magnetism and conductive materials, and have broad prospects. Transition metal dithioene complexes are often used as molecular magnets because of delocalized conjugated systems and have received much research interests due to their intrinsic features of electrical conductivity, magnetism and nonlinear optics.

In this work, a metal dithioene complex (BrBnMeIm)Ni(mnt)₂ was obtained. The single crystal was produced by solvent volatilization method. The crystal structure of the compound was characterized by X-ray diffraction, and its thermal stability and magnetism were studied by means of thermogravimetry, DSC and susceptibility measurement. The results show that (BrBnMeIm)Ni(mnt)₂ crystal belongs to triclinic system, the space group is P-1, and the [Ni(mnt)₂]^- anion and BrBnMeIm cation form alternated layer stacking. In the anion packed column, anions were accumulated by face-to-face, and there may be exhibiting spin dimerization exchange. In the X-ray powder diffraction spectrum, the diffraction peak of (BrBnMeIm)Ni(mnt)₂ powder is basically the same as that of its simulated PXRD patterns, which shows that the as-prepared crystal has high phase purity. In TGA curve, it illustrates that there is no obvious weight loss of (BrBnMeIm)Ni(mnt)₂ compound from room temperature to 566 K, indicating that it has good thermal stability. The measurement of magnetic susceptibilityshows that there is a magnetic phase transition in the range of 0-400 K, but the transition temperature is 243 K and the phase transition temperature point in the DSC test (a small thermal response endothermic peak appears at 239 K) is close but not completely consistent, but we do not have enough evidence to prove that a structural phase change was occurred.

Keywords: [Ni(mnt)₂]^n-, magnetic properties,structural phase transition,crystal structure

目录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1分子基磁性材料 1

1.1.1有机自由基分子磁体 1

1.1.2金属-有机自由基分子磁体 2

1.1.3金属配合物分子磁体 2

1.1.4单分子磁体 3

1.2自旋转换磁双稳态材料 4

1.2.1自旋交叉配合物 4

1.2.2 spin-Peierls相变 5

1.2.3价态异构(价态互变)化合物 7

1.2.4结构相变 8

1.3金属二硫烯配合物 9

1.3.1二硫烯配合物的磁性质 9

1.3.2二硫烯配合物的光学性质 10

1.3.3二硫烯配合物的电子传输性质 12

1.4本课题意义 12

第二章 [Ni(mnt)₂]^-配合物的结构设计和磁电性质 14

2.1前言 14

2.2实验部分 14

2.2.1原料和试剂 14

2.2.2化合物合成 14

2.2.3单晶培养 15

2.2.4分析测试仪器和方法 16

第三章 结果与讨论 18

3.1 晶体结构分析 18

3.2 相纯度分析 21

3.3 热稳定性分析 22

3.4 DSC分析 23

3.5 磁化率Χ_m 24

第四章 结论与展望 26

4.1 结论 26

4.2 展望 26

参考文献 27

致谢 30

1. 绪论

1.1分子基磁性材料

随着社会的进步和科技的发展，人们不再局限于对仅具有单一功能材料的研究，更多的致力于多功能材料的开发与研究。具有多种功能的分子基磁性材料，近年来被发现具有多种多样的化学和物理性质，在多种领域都具有优良的发展前景，如催化、光学材料、导电材料等。^[4]近年来随着研究的进展，分子基磁性材料相比传统的铁磁体表现出了极大的优势，传统的磁体通常采用冶金学或者某些物理方法制备，在加工的过程中需在高温条件冶炼，造成大量的磁损耗；而分子基磁体大多采用无机或有机等化学方法合成，通常易溶于普通的有机油溶剂，便于加工，所制得的产物磁损耗小、相对密度轻，而且体积小、结构多样。^[11],[20]分子基磁性材料顾名思义是由分子组成且具有磁性特征的材料。^[49]通常系指由有机分子、金属有机分子或金属配合物构成的功能材料^[27]。

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