![The Synthesis of [Sn10(Si(SiMe3)3)4]2- Using a Metastable Sn(I) Halide Solution Synthesized via a Co-condensation Technique](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F54498.jpg&w=3840&q=50)
B ((C6F5) 3−対Al ((C6F5) 3) 派生メタルロセニウムイオンペア. 構造的,熱化学的,構造的ダイナミクスの差異
Nicholas G Stahl1, Michael R Salata, Tobin J Marks
1Department of Chemistry, Northwestern University, Evanston, IL 60208-3113, USA.
Journal of the American Chemical Society
|August 4, 2005
まとめ
アルミニウム (Al) (C6F5) 3) のコカタリストは,グループ4のメタルロセニウムイオンペアにおけるボロン (B) (C6F5) 3) の同位体よりもメチドの afinity が低いことを示しています. これにより,より強いブリッジングメチル群結合と,Al-derivedシステムに対する変化したエピメリゼーション運動性が得られます.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- メイングループ 化学
背景:
- メタロセニウムイオンペアは,オレフィンポリメリゼーション触媒において極めて重要です.
- カウンターアニオンの選択は,触媒の活性と安定性に大きく影響する.
- B ((C6F5) 3) のようなボロン基フッロアリル化合物は,一般的な活性化剤ですが,アルミニウム類に比べてその性質は完全に理解されていません.
研究 の 目的:
- Al (C6F5) 3系とB (C6F5) 3系グループ4のメタルロケニウムイオンペアの熱力学および構造的性質を定量的に比較する.
- 橋渡しメチル群の結合強度と,その後のイオンペアエピメリゼーション動態に対する対アンイオンの影響を調査する.
- Al (C6F5) 3とB (C6F5) 3) の間のメチド afinityの違いを明らかにする.
主な方法:
- rac-C2H4(eta5-Ind) 2Zr(CH3) 2とB(C6F5) 3またはAl(C6F5) 3を使用したメタルロセニウムイオンペアの合成.
- イオンペアの構造特性を決定するX線結晶学.
- イソペリボルの溶液カロミテリーは,イオンペア形成エンタルピーを測定する.
- 変数温度 (VT) 核磁共鳴 (NMR) スペクトロスコーピーは,イオンペアエピメリゼーション (コカタリスト交換とアニオン交換) の運動パラメータを決定します.
主要な成果:
- Al ((C6F5) 3) 派生イオンペアは,B ((C6F5) 3) 派生イオンペアと比較して弱いメチド親和性を表しており,これは低いイオンペア形成エンタルピーによって証明されています.
- X線結晶学では,Al ((C6F5) 3) 派生イオンペアのブリッジングメチル群がより抽象化されず,より長いZr-CH3ブリッジングボンドの長さにつながることを明らかにしています.
- 動的研究によると,ブリッジングメシドは,Al ((C6F5) 3) 派生イオンペアでより強く結合しており,エピメリゼーションの活性化バリアが高くなる.
結論:
- Al ((C6F5) 3) は,B ((C6F5) 3) よりも著しく弱いルイス酸であり,メチドの afinity が低いことを示しています.
- Al-derivedとB-derivedのイオンペアの構造と熱力学的違いは,メタルロセニウム触媒の安定性と反応性に影響を及ぼします.
- これらの発見は,特定のポリメリゼーションアプリケーションのためのカスタマイズされたコカタリストの設計に貴重な洞察を提供します.
さらに関連する動画
12:02Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique
Published on: November 3, 2017
07:20Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods
Published on: October 6, 2023
関連する概念動画
02:48Ionic Bonding and Electron Transfer
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
02:37Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
02:45Alkyl Halides
Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
01:04Structures of Aldehydes and Ketones
Vanillin—a flavoring agent in vanilla, cinnamaldehyde—a molecule responsible for the distinct smell of cinnamon, and acetone—a strong-smelling ingredient in nail polish removers, all belong to a class of carbonyl compounds called aldehydes and ketones (Figure 1). Although both aldehydes and ketones contain the characteristic carbonyl (C=O) bond, their chemical structures vary with respect to the groups directly attached to the carbonyl carbon.
In aldehydes (Figures 1a and 1b), the carbonyl...
In aldehydes (Figures 1a and 1b), the carbonyl...