一氧化碳诱导的二裂变与4组金属:反应范围和合以形成N-H键和CO脱氧化
Donald J Knobloch1, Emil Lobkovsky, Paul J Chirik
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|July 29, 2010
概括
一氧化碳 (CO) 诱导氧化 (N2) 在和复合体中裂变,形成氧化胺连接物. 哈夫尼复合物比更清洁的N2裂变,进一步的反应产生异酸复合物.
科学领域:
- 有机金属化学 有机金属化学
- 无机化学 无机化学 有机化学
- 催化剂是一种催化剂.
背景情况:
- 二 (N2) 激活是化学中的一个关键挑战,因为它具有强大的三重键.
- 金属复合物为研究N2裂变反应提供了一个多功能平台.
- 了解N2裂变机制对于固和材料科学至关重要.
研究的目的:
- 调查一氧化碳 (CO) 诱导的N2裂变在和复合物的范围.
- 阐明反应路径并确定产生的产品.
- 探索金属 (Zr与Hf) 和体环境对N2裂变的影响.
主要方法:
- 齐尔科诺和哈夫诺二化合物的合成和表征.
- 这些复合体在各种条件下与CO发生反应.
- 谱学分析 (NMR,X射线晶体学) 用于确定产品结构.
- 研究与H2,乙烯和西兰酸盐的反应.
主要成果:
- 在conocene和hafnocene复合体中观察到CO诱导的N2裂变,形成桥梁氧化胺连接体.
- 与复合物相比,复合物表现出更清洁的N2裂变,而复合物显示出竞争性的二损失.
- 与H2或乙烯的反应导致异酸金属复合物与桥接的imido连接物.
- 一个Ansa-hafnocene复合物在与silanes反应时产生了异酸 hafnocene mu-oxo化物,表明N2和CO的裂变.
结论:
- 碳化合物是一种有效的试剂,用于裂解金属复合体中的强N2键.
- 金属和连接物的电子和固态特性显著影响N2裂变路径和效率.
- 这项研究提供了有关催化和化学的新N2转化途径的见解.
相关概念视频
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for the...
Aldehydes and Ketones to Alkanes: Wolff–Kishner Reduction
Wolff–Kishner reduction involves converting aldehydes and ketones to alkanes using hydrazine and a base. The reaction converts a carbonyl group to a methylene group. The method was independently discovered by N. Kishner in 1911 and L. Wolff in 1912. The reduction is carried out in high-boiling solvents such as ethylene glycol and diethylene glycol because heat is required to deprotonate the N–H proton in one of the reaction steps.
Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Alkynes to Carboxylic Acids: Oxidative Cleavage
Alkynes undergo oxidative cleavage in the presence of oxidizing reagents like potassium permanganate and ozone. The triple bond — one σ bond and two π bonds — is completely cleaved, and the alkyne is oxidized to carboxylic acids. When warm and basic aqueous potassium permanganate is used as an oxidizing agent, alkynes are first converted to carboxylate salts via an unstable α-diketone intermediate. Further, a mild acid treatment protonates the carboxylate anions generating free carboxylic acid...
Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
Aldehydes and Ketones with HCN: Cyanohydrin Formation Mechanism
Cyanohydrins are formed when cyanide nucleophiles and carbonyl compounds like aldehydes and ketones react. A strong base, the cyanide ion, catalyzes cyanohydrin formation. The ions are generated from HCN under aqueous conditions. Once the cyanide ions are generated, the first step involves the nucleophilic attack of the cyanide ions on the electrophilic carbonyl carbon. This attack shifts the π electrons from the C=O to the oxygen atom forming the alkoxide ion intermediate. The alkoxide anion...


