一个减少的β-diketiminato结合的Ni3H4单元催化H/D交换
Stefan Pfirrmann1, Christian Limberg, Christian Herwig
1Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Strasse 2, 12489 Berlin, Germany.
Journal of the American Chemical Society
|September 11, 2010
概括
研究人员利用石墨探索了化二元体的减少. 这导致了新型三核化复合物的发现,这是同类中第一个,表现出独特的化学特性和电子结构.
科学领域:
- 有机金属化学 有机金属化学
- 协调化学 协调化学
- 无机合成 无机合成
背景情况:
- 研究了一种β-diketiminato(II) 化二聚物[LNi(μ-H) ((2) NiL]的逐步减少,标记为1.
- 探索与石墨 (KC(8) 的反应,以实现控制的复合物的减少和合成.
研究的目的:
- 通过逐步减少合成和表征新的化复合物.
- 研究由此产生的多核化合物的结构,电子和化学特性.
主要方法:
- 使用石墨逐步减少 (((II) 化物二聚物.
- 单晶X射线衍射用于化合物的结构确定 3-6.
- 电子结构分析的EPR和NMR光谱,磁性测量和DFT计算.
主要成果:
- 合成一种混合价值的Ni (I) /Ni (II) 复合物 (3) 和一个三核化复合物 (4) 具有一个Ni (II) 和两个Ni (I) 中心.
- 化合物4是第一个具有结构特征的分子化合物,它由三个原子与化物连接而成,呈现出反铁磁合和单个基态.
- 证明了化合物4的独特反应性,包括单电子氧化到Ni (II) (Ni) (II) 的物种 (5) 和与CO反应以形成碳化合物 (6),以及H/D交换能力.
结论:
- 成功合成和表征了新的化复合物,扩大了多核化学的范围.
- 三核复合体4代表了金属化物集群研究的重大进步,为其电子结构和反应性提供了洞察力.
- 观察到的H/D交换和与CO的反应性突显了这些复合物在催化和进一步合成转化中的潜力.
相关概念视频
00:55Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
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01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
01:18Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
01:20Amides to Amines: LiAlH4 Reduction
Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.