移行金属形式複合体のヒドリドドナー能力と結合解離の自由エネルギー
William W Ellis1, Alex Miedaner, Calvin J Curtis
1National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, USA.
Journal of the American Chemical Society
|February 28, 2002
まとめ
研究者は,ホルミール複合体のヒドリドネーション能力を定量化し,約50kcal/molの値を発見しました. この研究は,有機金属化学におけるヒドリド移転反応の理解を前進させる.
科学分野:
- 有機金属化学 有機金属化学
- 反応メカニズム 反応メカニズム
- 熱力学は熱力学である.
背景:
- ハイドリド移転は,有機金属化学における重要な反応である.
- ハイドリドドナー能力の定量化は,反応性を理解するために重要である.
研究 の 目的:
- フォーミル複合体のヒドリドネーション能力を決定する.
- 構造とヒドリドドネーションの関係を調査する.
- 水素原子によるレニウムカルボニル複合体のドナー能力の測定.
主な方法:
- 水素移転反応の動力学と均衡の測定.
- リドックスポテンシャルを判定するためのサイクルボルトメトリー.
- DeltaGdegrees ((H-) の熱力学的計算について.
主要な成果:
- フォルミル複合体のヒドリドネーション能力は44~55kcal/molである.
- 水素原子のドナー能力を持つレニウムカルボニル複合体は,約50 kcal/molである.
- プラチナヒドリド複合体を用いて,ヒドリドがレニウムホルミール複合体に移行する量を測定した.
結論:
- この研究は,ホルミール複合体のヒドリド提供能力の定量的な尺度を提供する.
- レドックスポテンシャルは,水素原子のドナー能力と相関しています.
- この研究は,ヒドリド移転機構の理解に貢献します.
関連する概念動画
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
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...
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.
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...