モノサイクルボロンカルボニル:新しい芳香化合物
Hai-Shun Wu1, Haijun Jiao, Zhi-Xiang Wang
1Department of Chemistry, Shanxi Normal University, Linfen 041004, China.
Journal of the American Chemical Society
|April 10, 2003
まとめ
単環ボロンカルボニル (BCO) nmは4n + 2の離位電子を示し,高芳香性を示しています. この結論は,核独立化学シフト (NICS) の計算とベンゼン同類との比較によって裏付けられています.
科学分野:
- * コンピューティング・ケミストリー
- * 無機化学 無機化学
- * アロマティック性に関する研究
背景:
- *ボロンカルボニルは,潜在的芳香性を持つ無機化合物である.
- *これらの化合物の芳香性を理解することは,それらの安定性と反応性を予測するために重要である.
- * 過去の研究では,様々なボロンを含む分子の電子構造を調査した.
研究 の 目的:
- *単環ボロンカルボニル (BCO) nm.nm.の芳香度を調査する.
- *4n + 2の離位電子を持つ (BCO) nm化合物が芳香特性を有するかどうかを判断する.
- *これらのボロンカルボニルの芳香度をベンゼンと比較するために.
主な方法:
- * 核独立化学シフト (NICS) 計算を行いました.
- * 電子エネルギーが計算され,ベンゼンの類型と比較されました.
- * (BCO) nmシステムにおける電子移位を分析した.
主要な成果:
- *4n + 2の離位電子を持つ単環ボロンカルボニル (BCO) nmは,非常に芳香性があることが判明しました.
- *計算されたNICS値は,有意な芳香特性を示した.
- *計算されたエネルギーは,よく知られている芳香化合物であるベンゼンとの類似性を支持しました.
結論:
- *4n + 2の離位電子を持つ単環ボロンカルボニルは,確かに非常に芳香的です.
- *これらの発見は,ボロンを含む無機システムに対する芳香性概念の適用性を確認しています.
- *この研究は,新しい芳香無機化合物の設計と合成のための理論的基礎を提供します.
関連する概念動画
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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.
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.
Aromatic Hydrocarbon Anions: Structural Overview
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous overlap of p...
Due to the absence of continuous overlap of p...
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.
Frost Circles for Different Conjugated Systems
The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.
Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...


