B22-和B23-:是烯和烯的全类同类
Alina P Sergeeva1, Zachary A Piazza, Constantin Romanescu
1Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.
Journal of the American Chemical Society
|October 4, 2012
概括
大集群B(22) (((-) 和B(23) ((-) 显示出令人惊的平面结构和结合. 这些集群模仿多环芳碳化合物,如 antracen 和 phenanthrene.
科学领域:
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
背景情况:
- 团表现出独特的大小依赖的结构和结合.
- 了解这些特性是开发基于的新型纳米结构的关键.
研究的目的:
- 为了研究22和23原子团的结构和化学键.
- 为了比较它们的特性与散装和已知的分子类似物.
主要方法:
- 结合光电子光谱学和初始计算.
- 电子结构和化学结合的分析.
主要成果:
- B(22)(-) 呈现出一个准平面的,稍微曲的三角格子.
- B(23)(-) 形成了一个完全平的,心形的星团,有一个五角形的空洞.
- 两个都显示了与多环芳相似的非局部化π电子系统.
结论:
- 经过实验鉴定的最大的负集群,B(22) ((-) 和B(23) ((-),作为和的全类型.
- 团可以在大尺寸上保持平面性,表现出新的结合模式.
相关概念视频
Nomenclature of Aryl and Heterocyclic Amines
The simplest aromatic amine is phenylamine, which contains an –NH2 functionality directly attached to an aromatic ring. The name aniline is designated for this skeleton. As shown in Figure 1, the common names of the functionalized anilines involve prefixes ortho-, meta-, and para- to indicate the substitution position. Different functionalized aniline derivatives also have notable trivial names.
Nomenclature of Aromatic Compounds with a Single Substituent
Benzene is the simplest aromatic hydrocarbon or arene. The IUPAC names for simple monosubstituted benzene derivatives are derived by adding the substituent's name as a prefix to the parent benzene. For example, halobenzene, where the halogen could be fluoro (F), chloro (Cl), bromo (Br), and iodo (I).
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
NMR Spectroscopy of Benzene Derivatives
Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm in the 1H NMR spectrum. The observed shift is far downfield because the aromatic ring current strongly deshields the protons. Any substitution on the benzene ring makes the aromatic protons nonequivalent, and the protons split each other. The peak is, therefore, no longer a singlet and the splitting pattern and their associated coupling constants depend...
Five-Membered Heterocyclic Aromatic Compounds: Overview
Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom, respectively.


