単純なアミドおよびアロキシドリガンドによるTmII,DyII,NdIIによる二酸化窒素還元
William J Evans1, Gaël Zucchi, Joseph W Ziller
1Department of Chemistry, University of California, Irvine, CA 92697-2025, USA. wevans@uci.edu
Journal of the American Chemical Society
|January 8, 2003
まとめ
新しい研究によると,トゥリウム (Tm),ディスプロシウム (Dy),ネオジミウム (Nd) のような二価ランタニドは,窒素ガス (N2) を新しい平面構造に減らすことができます. このブレークスルーでは,複雑なリガンドを避け,単純なアミドおよびアリロキシドリガンドを二酸化窒素還元に使用しています.
科学分野:
- 無機化学 無機化学とは
- 有機金属化学 有機金属化学
- 窒素固定装置による窒素固定
背景:
- 窒素ガス (N2) は豊富であるが,惰性であり,化学的還元に重大な課題をもたらす.
- 伝統的なN2還元方法は,しばしば厳しい条件や複雑なリガンド系を必要とします.
- 二重ランタニド複合体は,N2の活性化と還元を研究するための新しい道を開く.
研究 の 目的:
- 二価ランタニド複合体の二酸化窒素 (N2) の減少の可能性を調査する.
- ランタニドによるN2還元を促進するために,シンプルで一般的なリガンドの使用を調査する.
- 窒素を減らした製品の構造と結合を特徴づける.
主な方法:
- 二価ランタニド複合体の合成 (LnI2,ここでLn = Tm, Dy, Nd).
- LnI2がナトリウムビス・トリメチルシリル・アミド (NaN・SiMe3) 2) またはカリウムアリオキシド (KOC6H3tBu2-2,6) と反応する.
- X線結晶学を用いた結果の二酸化窒素複合体の構造的特徴.
主要な成果:
- アミドリガンドによる二価TmとDy複合体はN2を還元し,NN結合長が1.264{\displaystyle 1.264} (7) と1.305{\displaystyle 1.305} (6) のNN結合長を持つ平面的なLn2N2単位を形成し, (N2) 2−部分を示す.
- アリロキシドリガンドと二価なNd複合体は,1.242(7) Åの短いNN結合長を持つ類似の平面Nd2N2構造を形成した.
- 減少は,サイクロペンタディエニルまたはポリデント酸リガンドなしで達成されました.
結論:
- 二重ランタニド (Tm,Dy,Nd) は,二酸化窒素 (N2) の効果的還元剤である.
- これらの二価ランタニドによるN2還元には,単純なモノデントアミドとアリロキシドリガンドが十分である.
- この研究は,アクセシブルなランタニド複合体を用いて,窒素固定のための新しい,潜在的に単純な経路を示しています.
関連する概念動画
01:24Redox Reactions
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
02:23Alcohols from Carbonyl Compounds: Reduction
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
01:19Acid Halides to Alcohols: LiAlH4 Reduction
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
01:26Redox Titration: Other Oxidizing and Reducing Agents
Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and K2Cr2O7. The choice of oxidizing titrants depends on factors like stability, cost, analyte strength, and reaction rate between the analyte and titrant. KMnO4 is a strong oxidizing titrant that reduces from Mn(VII) to Mn(II) in a highly acidic solution, simultaneously oxidizing the analyte to a higher oxidation state. In this case, KMnO4 acts as a...
01:19Masking and Demasking Agents
EDTA titrations may necessitate masking and demasking agents to temporarily protect a particular metal ion in a mixture from the EDTA reaction. These agents facilitate the sequential analysis of the metal ions by forming stable complexes with some—but not all—metal ions during certain steps.
There are many masking agents, such as cyanide, fluoride, triethanolamine, thiourea, and 2,3-bis(sulfanyl)propan-1-ol (formerly 2,3-dimercapto-1-propanol), with the masking agent chosen based on the metal...
There are many masking agents, such as cyanide, fluoride, triethanolamine, thiourea, and 2,3-bis(sulfanyl)propan-1-ol (formerly 2,3-dimercapto-1-propanol), with the masking agent chosen based on the metal...
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...