对六核Cu (II) 和Ni (II) 聚氧酸复合物的磁性行为进行理论研究
Eliseo Ruiz1, Joan Cano, Santiago Alvarez
1Departament de Química Inorgànica and Centre de Recerca en Química Teòrica (CeRQT), Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain.
Journal of the American Chemical Society
|May 29, 2003
概括
本研究使用密度函数理论探索铜 (Cu) 和 (Ni) 复合体中的磁相互作用. 它估计了这些桥梁集群中不同邻近的金属离子的交换合常数.
科学领域:
- 计算化学计算化学
- 无机化学 无机化学 有机化学
- 材料科学 材料科学 材料科学
背景情况:
- 了解磁交换合对于设计分子磁铁和先进材料至关重要.
- 聚氧酸桥接金属复合物为研究磁相互作用提供了一个多功能平台.
- 铜 (Cu(II)) 和 (Ni(II)) 的六核复合体由于其潜在的磁性特性而引起人们的兴趣.
研究的目的:
- 从理论上研究Cu (II) 和Ni (II) 的六核多氧酸桥复合体中的交换合相互作用.
- 为了确定第一个,第二个和第三个邻居交换合常量.
- 为了比较原始和改性 (结合) Ni 复合物的磁性特性,以及双核类似物.
主要方法:
- 使用密度函数理论 (DFT) 的计算.
- 计算了三种不同的自旋配置的能量.
- 在各种结构模型上进行了计算,包括六核集群和双核类型.
主要成果:
- 获得了第一,第二和第三邻交换合常数的估计.
- 这项研究分析了结构变化的影响 (原始与chloroenclathrated) 在磁性合.
- 对比分析包括Cu和Ni原始集群,结合的Ni复合体,以及M(2)Zn(4) 双核类型.
结论:
- 理论研究为这些金属复合体中的磁交换相互作用的性质和规模提供了宝贵的见解.
- 这些发现有助于对多核系统中磁性合机制的基本理解.
- 结果可以指导新材料的合成和设计,这些材料具有量身定制的磁性.
相关概念视频
02:32Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...