B22-およびB23-:アントラセーンとフェナントレンの全ボロンアナログである
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
まとめ
大型のボルンクラスターB (((22) (((-) とB (((23) ((-) は,驚くべき平面構造と結合を明らかにしています. これらのボロンクラスターは,アントラセーンやフェナントレンなどのポリサイクル芳香炭化水素を模倣する.
科学分野:
- 物理化学 物理化学
- マテリアルサイエンス 材料科学
- ナノテクノロジー ナノテクノロジー
背景:
- ボロンクラスターは,サイズに依存するユニークな構造と結合を示しています.
- これらの性質を理解することは,新しいボロンベースのナノ構造の開発の鍵です.
研究 の 目的:
- 22原子と23原子のボロンクラスターの構造と化学結合を調査する.
- 質量ボロンおよび既知の分子類似体との性質を比較するために.
主な方法:
- 組み合わせた光電子スペクトロスコーピーとアビニシオ計算.
- 電子構造と化学結合の分析.
主要な成果:
- B(22)(-) は準平面で,わずかに曲がった三角形の格子を示しています.
- B(23)(-) は,五角形の空洞を持つ完璧に平らな,心臓の形状のクラスタを形成します.
- 両クラスターとも,ポリサイクル芳香炭化水素に類似した非局所化されたπ電子系を示している.
結論:
- 実験的に特徴づけられた最大の負ボロンクラスターであるB(22) ((-) とB(23) ((-) は,アントラセーンとフェナントレンの全ボロン類似体として機能する.
- ボロンのクラスターは,大きなサイズでも平面性を保ち,新しい結合パターンを示します.
関連する概念動画
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.


