超臨界水における均質な酸化触媒 Mn (II) (Br) (-1) (x) の構造:X線吸収微細構造の研究
Yongsheng Chen1, John L Fulton, Walter Partenheimer
1Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Journal of the American Chemical Society
|October 6, 2005
まとめ
超臨界水では,マンガン (((II) ブロミド触媒は,八面体構造から四面体構造に変化し,テレフタル酸合成に不可欠なMn-Br接触イオンペアを形成します.
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
- カタリシス カタリシス カタリシス
背景:
- 超臨界水中のマンガン (II) ブロミド (MnBr2) は,テレフタル酸のエアロビック酸化合成を効果的に触媒化する.
- Mn (II) と Br (-1) イオンの協調構造を理解することは,この触媒活動の説明の鍵です.
研究 の 目的:
- 超臨界水におけるMn (II) とBr (-1) イオンの第1殻の調整構造を解明する.
- メチラロマティック化合物の酸化におけるMnBr2の触媒的役割の構造的基礎を明確にするために.
主な方法:
- 拡張X線吸収精細構造 (EXAFS) とX線吸収近縁構造 (XANES) のスペクトロスコピーを利用しました.
- アルゴン国立研究所のAdvanced Photon SourceでMnとBrKのエッジスペクトルを収集しました.
主要な成果:
- Mn(II) の調整は,八面体 (環境) から四面体 (超臨界条件) に変化する.
- 超臨界水では,Mn-OH2とMn-Brの結合距離はそれぞれ2.14 Åと2.46 Åである.
- 溶解したMnBr2は[Mn(II) ((H2O) 6+2から[Mn(II) ((H2O) 2 ((Br ((-1)) 2に変換され,Mn-Br接触イオンペアを形成する.
結論:
- 超臨界水中の活性MnBr2触媒は,2つのMn-Br接触イオンペアを持つ四面体構造を示しています.
- 過剰なブロミドイオンはブロミドの協調性を高め,水のリガンドを減少させます.
- アセテートアニオンは,不溶性マンガン酸化物 (MnO) を形成することによって触媒を無効化する.
さらに関連する動画
07:55Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering
Published on: April 17, 2018
09:02Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of Manganese(II) Acetylacetonate
Published on: June 18, 2020
関連する概念動画
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
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...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
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.
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.
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...