結晶学的に特徴づけられるBis (cyclopentadienyl) Sc (II) コンプレックス: (C5H2tBu3) 2Scと{[C5H3(SiMe3) 22</>ScI}1
Joshua D Queen1, Lauren M Anderson-Sanchez1, Cary R Stennett1
1Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
Journal of the American Chemical Society
|January 24, 2024
まとめ
研究者は,大型リガンドを使用して,最初の結晶学的に特徴づけられたスカンジウム (II) ビス (cyclopentadienyl) コンプレックス,Cpttt2Scを合成した. この進歩は低価移行金属化学の研究に新たな道を開く.
科学分野:
- 有機金属化学
- 無機化学
- 移行金属複合体
背景:
- スカンジウム (Scandium) は,第1列の移行金属であり,様々な酸化状態を示し,合成上の課題により,Sc (II) はあまり探求されていない.
- ビス ((cyclopentadienyl) コンプレックス,またはメタロセンは,触媒と材料科学において重要であるが,その低価変種は稀である.
- ステリカルに要求されるサイクロペンタディエニルリガンドは,異常な酸化状態と調整幾何学を安定させるためにしばしば使用されます.
研究 の 目的:
- 新しいビス (cyclopentadienyl) スカンジウム (II) 複合体を合成し,特徴づけること.
- スカンジウムの酸化状態と複合体の安定性に対する異なるサイクロペンタディエニルリガンド (Cpttt,Cp*,Cp′′) の影響を調査する.
- 低値の有機金属化合物に アクセスするための合成経路を探る
主な方法:
- スカンジウムヨウ酸化物前駆体 (Cpttt2ScI,Cp*2ScI,Cp′′2ScI) の合成
- カリウム・グラファイト (KC8) または,クラウン・エーテル/クリプトンズの存在によるカリウムを用いた還元法.
- X線結晶学,EPR光譜学,昇華,融点決定を含む特徴化技術.
- 密度関数理論 (DFT) を用いた計算研究.
主要な成果:
- 最初のスカンジウム (II) ビス (cyclopentadienyl) コンプレックス,Cpttt2Sc (2) の合成と結晶学的な特徴付けが成功し,広環中心体-Sc-環中心体角 (170.6°) が特徴付けられた.
- EPRスペクトロスコピーは,Cptt2Sc (2) とCp*2ScI還元から派生した中間種 (4) のSc(II) 酸化状態を確認した.
- Cp*およびCp′′リガンドでSc(II) コンプレクスを分離する試みは,Sc(III) 製品または[K(crypt) ][Cp′′2ScI] (5) のような熱的に不安定なSc(II) 種を生成した.
- DFT計算は,合成された複合体の電子構造とステリック特性 (Guzei方法) に関する洞察を提供した.
結論:
- Cptttリガンドのステリック塊は,安定したSc (II) bis (cyclopentadienyl) 複合体の分離と特徴づけに不可欠である.
- 還元条件と溶媒の選択は,スカンジウム金属素前駆体を含む反応の結果に大きく影響する.
- この研究は,低価初期移行金属メタロセンの化学に関するさらなる研究のための基盤を確立する.
さらに関連する動画
10:17Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
6.9K
12:27Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
10.9K
関連する概念動画
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
42.6K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
42.6K
02:52Stereoisomerism
11.9K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
11.9K
02:42Valence Bond Theory
8.6K
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...
8.6K
01:16Cycloaddition Reactions: Overview
2.6K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
2.6K
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
4.6K
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
4.6K
02:34Structural Isomerism
19.2K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
19.2K