固体/水界面における多核金属イオン複合体の証拠は,X線吸収スペクトロスコーピーによるX線吸収スペクトロスコーピーによる
C J Chisholm-Brause1, P A O'Day, G E Brown
1Aqueous and Surface Geochemistry Group, School of Earth Sciences, Stanford University, California 94305-2115.
Nature
|December 6, 1990
まとめ
X線吸収スペクトロスコピーは,鉱物表面の多核コバルト複合体を明らかにしました. 異なる鉱物タイプによって表面の複雑な構造が変化し,金属イオン吸収モデルに影響を与えます.
科学分野:
- 環境化学 環境化学
- 地質化学 地質化学
- マテリアルサイエンス 材料科学
背景:
- 天然水中の金属は鉱物に吸収され,その行動や輸送に影響を及ぼします.
- 固体/水界面の化学を理解することは,金属の振る舞いを予測する上で極めて重要です.
- X線吸収光譜法 (XAS) は,表面の複雑な構造と結合を特定します.
研究 の 目的:
- ガンマ-Al2O3,ルチル (TiO2),カオリニットに吸収された二価コバルト (Co(II)) 複合体の構造を調査する.
- 異なる鉱物表面が金属ソープション複合体の形成に及ぼす影響を決定する.
- 精密な金属イオン吸収モデリングのための洞察を提供するために.
主な方法:
- X線吸収光譜法 (XAS) が採用されました.
- 二価コバルト (Co(II)) の吸収は,ガンマ-Al2O3,ルチル (TiO2) およびカオリニットで研究されました.
- 最も近い隣の原子,原子間距離,複雑な構造について分析されたスペクトロスコピーデータ.
主要な成果:
- 単層の覆面の下には,多核のCo ((II)) 吸収複合体の直接的な証拠が見つかりました.
- コーディネート原子と原子間距離の明確な差異は,3つの固体上のCo ((II) について観察されました.
- 表面上の複雑な構造は,鉱物基板に基づいて著しく変化した.
結論:
- 酸化物や粘土を含む鉱物表面は,水性表面複合体の構造に影響を与えます.
- この発見は,金属吸収における表面特異相互作用の重要性を強調しています.
- 精密な金属イオン吸収モデルは,鉱物の表面特性を考慮する必要があります.
関連する概念動画
03:13Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
03:45Formation of Complex Ions
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
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...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
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...
00:43Complexometric Titration: Ligands
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...