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Updated: Jun 20, 2026
07:36
Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
Mo-Moの4倍債券から5倍債券への旅
Yi-Chou Tsai1, Hong-Zhang Chen, Chie-Chieh Chang
1Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC. yictsai@mx.nthu.edu.tw
Journal of the American Chemical Society
|August 19, 2009
まとめ
研究者は,四重結合と五重結合を持つ新しいジモリブデンウム複合体を合成しました. これらの複合体は,DFT計算によって確認された,元素の第1行を超えて観測された最も短い金属対金属債券を示しています.
科学分野:
- 無機化学 無機化学とは
- マテリアルサイエンス 材料科学
- コンピューティング・ケミストリー
背景:
- ディモリブデン複合体は,複数の金属対金属結合を示すことが知られている.
- パドルホイール構造は,ジモリブデン化学で一般的です.
- 高級金属対金属結合の探求は,化学結合の理解に不可欠である.
研究 の 目的:
- 四重,五重結合を持つ新しいジモリブデンウム複合体を合成し,特徴づけること.
- これらの新しい複合体の構造的および電子的性質を調査する.
- 最初の列の元素を超えた最短の金属対金属結合の形成を調査する.
主な方法:
- ダイモリブデン複合体の合成は,Li[RC][NDipp]]リガンドとK[4]Mo[5]Cl[6]の反応によって行われます.
- X線結晶学を用いた構造的特徴化.
- 密度関数理論 (DFT) の計算を用いた電子構造分析.
主要な成果:
- 2つのパドルホイール型四重結合ジモリブデン複合体,Mo(2)(mu-Cl)[Cl(2)Li(OEt(2))][mu-eta(2)-RC(N-2,6-i-Pr(2)C(6)H(3))(2)]を合成した.
- これらの複合体の減少により,Mo-Mo五重結合複合体,Mo(2) [mu-eta(2) -RC(N-2,6-i-Pr(2) C(6) H(3)) ((2)) ](2) が得られ,Mo-Mo結合の長さはかなり短かった.
- その結果得られるMo-Mo結合の長さは,第1列の元素を超えて観測された最も短い金属対金属結合を表しています.
結論:
- 四重結合と五重結合を持つジモリブデンウム複合体の成功合成は,無機化学における多重結合の範囲を拡大する.
- 観測された最短の金属対金属結合は,重過渡金属における結合の性質についての洞察を提供します.
- DFTの計算は,五重結合の存在と合成された複合体の構造的特徴を裏付けている.
関連する概念動画
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
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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 π orbitals.
01:08Spin–Spin Coupling Constant: Overview
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.
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01:28Multiple Halogenation of Methyl Ketones: Haloform Reaction
A method involving the transformation of methyl ketones to carboxylic acids using excess base and halogen is called the haloform reaction. It begins with the deprotonation of α hydrogen to form an enolate ion which reacts with the electrophilic halogen to give an α-halo ketone. The step continues until all the α protons are substituted to form a trihalomethyl ketone. The resulting molecule is unstable, and in the presence of a hydroxide base, it readily undergoes nucleophilic acyl substitution.
02:40Chemical Bonds
Atoms participate in a chemical bond formation to acquire a completed valence-shell electron configuration similar to that of the noble gas nearest to it in atomic number. Ionic, covalent, and metallic bonds are some of the important types of chemical bonds. Bond energy and bond length determine the strength of a chemical bond.
Types of Chemical Bonds
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01:13Five-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.