3座標のNi (III) -イミド複合体の合成と特徴付け
Vlad M Iluc1, Alexander J M Miller, John S Anderson
1Gordon Center for Integrative Science, Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA.
Journal of the American Chemical Society
|July 30, 2011
まとめ
研究者らは,新しいニッケル (III) -イミドを合成し,その電子および磁気特性を探求した. ステリック・バルクと電子系因子,特に2,6-デメシチルフェニル群は,これらの低座標ニッケル複合体の安定化に不可欠である.
科学分野:
- 有機金属化学 有機金属化学
- 無機化学 無機化学とは
- マテリアルサイエンス 材料科学
背景:
- 低コーディネートニッケル複合体は,そのユニークな反応性と電子構造により興味を惹きます.
- ニッケルイミドにおけるより高い酸化状態の安定化は,合成的な課題を提示する.
- ニッケルイミドの安定性に対する電子的およびステリック的影響を理解することは,触媒応用において極めて重要です.
研究 の 目的:
- 低調整ニッケルイミドの新しいファミリーを合成し,特徴づけること.
- アリルおよびアルキル置換剤によるニッケル (III) -イミドの電子および磁気特性を調査する.
- ニッケル・ナイトロゲン・コアの安定化におけるステリック・バルクの役割を明らかにする.
主な方法:
- 1,2-bis(di-tert-butylphosphino) ethaneでサポートされたニッケル ((II) 前駆物質の合成.
- ニッケル (II) 複合体の酸化によりニッケル (III) -イミドが形成されます.
- アリルとアルキルで置換されたニッケル (III) -イミドの分離と完全な特徴付け.
- 温度変数磁気測定と電子パラマグネティック共振 (EPR) スペクトロスコピー.
- 密度関数理論 (DFT) による計算.
主要な成果:
- アリルとアルキルが置換されたニッケル (III) -イミドの合成と特徴づけに成功した.
- 2,6-デメシチルフェニル置換剤は,Ni (III) -イミド分子を著しく安定させる.
- 温度変数磁気研究は,アリルとアルキル置換複合体の異なる性質を明らかにし,アルキル誘導体のスピン状態の均衡を示唆しました.
- DFTの計算は,イミド窒素上のペアレス電子の位置を確認し,水素原子抽象におけるアダマンチル置換物の反応性を強調した.
- 2,6-デメシチルフェニルグループのステリック効果は,NiNコアを保護し,分子構成に影響することを示した.
結論:
- 低調整ニッケルイミドの新しいファミリーが確立され,ニッケルの高酸化状態の洞察を提供している.
- 2,6-デメシチルフェニル群のステリック塊は,反応性ニッケル (III) -イミド種を安定させるために重要である.
- DFT計算は,電子構造,スピン状態,および反応性,特に水素原子抽象化に関する貴重な機械的洞察を提供します.
関連する概念動画
02:34Structural Isomerism
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 be...
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 be...
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...
02:54Coordination Compounds and Nomenclature
In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap with electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the seven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 1a). Transition metals do not normally bond in this fashion. They primarily form coordinate covalent bonds, a...
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.
01:23Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
01:16Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.