相关实验视频
Updated: Jul 4, 2026

06:45
Negative Additive Manufacturing of Complex Shaped Boron Carbides
Published on: September 18, 2018
碳避免了CB6 (((-),CB6 (((2-) 和C2B5 (((-) 平面碳-团中的超协调
Boris B Averkiev1, Dmitry Yu Zubarev, Lei-Ming Wang
1Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, USA.
Journal of the American Chemical Society
|June 28, 2008
概括
碳-集群 (CB6,C2B5和CB62) 采用独特的扭曲的七环结构. 之前提出的超协调结构被发现是不稳定的,结合分析解释了碳结构.
科学领域:
- 计算化学是一种计算化学.
- 量子化学是一种量子化学.
- 频谱学是一种光谱学.
背景情况:
- 了解小型碳-集群的结构和电子特性对于材料科学至关重要.
- 之前的研究表明,对于某些碳-系统,六环结构具有超协调的碳原子.
研究的目的:
- 确定CB6,C2B5和CB62集群的全球最低能量结构.
- 研究这些碳-系统的结合特性和稳定性.
- 解释这些平面星团中碳对高协调的偏好.
主要方法:
- 采用光电子光谱学来探测星团的电子状态.
- 使用Ab initio计算来建模结构和能量.
- 进行了详细的化学结合分析,以了解结合偏好.
主要成果:
- 对CB6,C2B5和CB62的全球最小结构被确定为扭曲的七环形态.
- 之前报告的具有高协调碳的六环结构被发现是能量不利的,并没有实验观察到.
- 化学结合分析揭示了碳避免超协调的原因.
结论:
- 扭曲的七环结构代表了CB6,C2B5和CB62集群的稳定配置.
- 超协调结构的能量不稳定性解释了在实验条件下它们的缺失.
- 了解这些集群中的结合,可以了解碳在相关材料中的行为.
相关概念视频
Hybridization of Atomic Orbitals I
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
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.
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...
Radicals: Electronic Structure and Geometry
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Valence 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...

