Tris ((9-fluorenylidene) メタンの2 Åを超える長い炭素-炭素結合
Takashi Kubo1,2, Yuki Suga1, Daisuke Hashizume3
1Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Journal of the American Chemical Society
|August 30, 2021
まとめ
研究者はフローレニル化合物における異常に長い炭素-炭素結合 (2.0 Å以上) を調査した. 実験的および計算的方法により,これらの拡張C−C結合における共性結合の相互作用が確認された.
科学分野:
- 有機化学
- 固体化学
- コンピュータ化学
背景:
- 炭素と炭素の結合は有機化学において基本的であり,通常は1.5~1.54 Åの範囲にある.
- 延長されたC-C結合の長さは,従来の結合理論と分子構造の理解に挑戦します.
研究 の 目的:
- 2.0 Å 以上のC−C 結合の形成と特徴を調査する.
- このような拡張C-C結合を備えたフローレニル化合物の電子構造と結合性質を分析する.
主な方法:
- 電子の分布を視覚化するためのX線電子密度マッピング.
- 固体炭素13核磁気共振 (NMR) スペクトロスコーピー
- アクティブ・スペース・セルフ・コンスタンスト・フィールド (CASSCF) の計算を完了する.
主要な成果:
- 垂直方向のフローレニル環によって形成された2.0 Åを超えるC−C結合の観測.
- 遠隔の炭素原子の 軌道が重なり合っていることがわかりました
- 最も高い占有分子軌道 (HOMO) と最も低い不占有分子軌道 (LUMO) の分析は,それぞれ2. 39 eVのギャップで相内および相外相互作用を示した.
- 固体13CのNMRでは,長結合炭素のピークが82.9ppmであった.
- CASSCF (6,6) の計算は,低レベルの過激性を示した.
結論:
- 実験的および理論的データは,例外的に長いC−C結合における共性結合の相互作用の存在を確認している.
- この研究は,従来とは異なる結合長を持つ分子の電子的および構造的性質に関する洞察を提供します.
関連する概念動画
Hybridization of Atomic Orbitals I
52.9K
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...
52.9K
Hybridization of Atomic Orbitals II
36.9K
sp3d and sp3d 2 Hybridization
36.9K
Spin–Spin Coupling Constant: Overview
1.1K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.1K
Conformations of Ethane and Propane
15.7K
In an organic molecule, free rotation about the carbon-carbon single bond results in energetically different conformers of the molecule. Due to this rotation, called the internal rotation, ethane has two major conformations — staggered and eclipsed.
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
15.7K
π Molecular Orbitals of 1,3-Butadiene
10.3K
Conjugated dienes have lower heats of hydrogenation than cumulated and isolated dienes, making them more stable. The enhanced stabilization of conjugated systems can be understood from their π molecular orbitals.
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
10.3K
¹H NMR: Long-Range Coupling
2.1K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.1K


