在Ba@C74的结构
Andreas Reich1, Martin Panthöfer, Hartwig Modrow
1Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany.
Journal of the American Chemical Society
|November 4, 2004
概括
这项研究使用先进的X射线衍射和光谱学揭示了金属烯的精确结构. 证实离子在富勒烯内偏离中心,为金属富勒烯化学提供了洞察力.
科学领域:
- 富勒烯化学 富勒烯化学
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
背景情况:
- 金属富勒烯是封装金属原子的富勒烯,在各种领域都有潜在的应用.
- 了解金属烯的精确结构和结合对于它们的发展至关重要.
- 以前的研究表明,在某些金属中,金属离子位置偏离中心,但直接的结构证据往往有限.
研究的目的:
- 为了确定单金属烯 Ba@C(74).Co(OEP).2C(6) H(6) 的详细晶体结构.
- 为了阐明离子在C74中的确切位置和协调.
- 为了研究这些复杂的金属烯单元的自组装和包装.
主要方法:
- 射频 (RF) 方法用于同时蒸发和碳.
- 三步高压液体染色法用于净化Ba@C(74).
- 单晶同步晶X射线 difraktion 在100K.
- Ba L(III) XANES光谱和量子化学计算用于结构验证.
主要成果:
- 首次确定了Ba@C(74).Co(OEP).2C(6) H(6) 的结构,揭示了高度局部化的内向性离子.
- 原子在C74中偏离中心,距离几何中心大约127-150分钟.
- Co(OEP) 分子形成二次体,协调富勒烯,复杂单元与溶剂分子组装成扭曲的六角包装.
结论:
- 使用实验和计算方法的组合,得出了标题化合物的一致和确的结构模型.
- 离子的离中心位置得到证实,为金属烯研究提供了关键的结构数据.
- 这些发现有助于更深入地了解内体金属烯的结构性质关系.
相关概念视频
Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
Lattice Centering and Coordination Number
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Structure of Benzene: Kekulé Model
In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
Structure of Benzene: Molecular Orbital Model
According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).


