マンガネスアルカン複合体:IRとNMRのスペクトル検査調査
James A Calladine1, Simon B Duckett, Michael W George
1School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
Journal of the American Chemical Society
|February 2, 2011
まとめ
新しいマンガンアルカン複合体は,光譜を用いて合成され,特徴づけられました. これらの発見は,特徴づけられたアルカン複合体の既知の範囲を拡大し,より不安定なマンガンの誘導体を含むようにしています.
科学分野:
- 有機金属化学 有機金属化学
- フォトケミストリー フォトケミストリー
- スペクトル顕微鏡検査です.
背景:
- 有機金属複合体は,触媒と材料科学において重要な役割を果たしています.
- アルカン複合体の特徴は,C−H結合の活性化に関する洞察を提供します.
- 以前の研究は,より安定したレニウムとロジウムアルカンの複合体に焦点を当てていた.
研究 の 目的:
- 新しいマンガン・アルカン複合体を合成し,特徴づけること.
- これらの複合体の安定性とスペクトル学的性質を調査する.
- NMRの特徴付けの範囲を,より不安定なマンガネス誘導体にも拡大する.
主な方法:
- アルカン溶媒 (プロパン,ブタン) で低温 (130-136 K) でCpMn(CO) ((3) を使用したマンガンアルカン複合体の光化学生成.
- フーリエ変換赤外線 (FTIR) 光譜法と陽子核磁気共鳴 ((1) H NMR) 光譜法による特徴付け.
- ダイナミックな研究のために,in situ レーザー光解と時間解像度IRスペクトロスコーピーを使用します.
主要な成果:
- CpMn ((CO) (((2) ((プロパン)) とCpMn ((CO) (((2) ((ブタン)) 複合体の形成は,IRスペクトロスコーピーで確認された (ν ((CO)) 帯域シフト).
- (1) H NMRスペクトルは,13Cラベリングのデュテレーションとカップリング定数 (JC-H) ≈120Hz) のシフトによる η(2) -CH陽子の特徴的な高場共鳴を示した.
- 異なるCpMn (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO)) CpMn (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (CO) (
結論:
- マンガン-アルカンの複合体を成功裏に合成し,特徴づけ,そのような化合物の既知のファミリーを拡大しました.
- NMRスペクトロシーは,より安定したレニウムおよびロジウム類に類似した,より不安定なマンガネス誘導体の特徴づけに有効であることが証明されました.
- この研究は,マンガン・アルカン複合体の構造,結合,および安定性に関する貴重なデータを提供します.
関連する概念動画
¹H NMR: Long-Range Coupling
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
¹H 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.
NMR Spectroscopy and Mass Spectrometry of Aldehydes and Ketones
In aldehydes, the hydrogen atom connected to the carbonyl carbon helps distinguish aldehydes from other carbonyl compounds using ¹H NMR spectroscopy. The closeness of aldehydic hydrogen to the electrophilic carbonyl carbon highly deshields the hydrogen atom causing its signal to appear around 10 ppm in the ¹H NMR spectra. α hydrogens split the aldehydic proton signal, which helps identify the number of α hydrogens in the molecule. For instance, one α hydrogen creates a doublet for an aldehydic...
NMR Spectroscopy of Benzene Derivatives
Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm in the 1H NMR spectrum. The observed shift is far downfield because the aromatic ring current strongly deshields the protons. Any substitution on the benzene ring makes the aromatic protons nonequivalent, and the protons split each other. The peak is, therefore, no longer a singlet and the splitting pattern and their associated coupling constants depend...
Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Radical Oxidation of Allylic and Benzylic Alcohols
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...


