电氧调节的乙烯与-硫酸盐复合物结合
Craig A Grapperhaus1, Kagna Ouch, Mark S Mashuta
1Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
Journal of the American Chemical Society
|December 17, 2008
概括
复合物的氧化状态决定了它们与乙烯的可逆结合能力. 这种对碳-硫键形成的控制允许调节性乙烯的吸收和释放,这对于催化应用至关重要.
科学领域:
- 有机金属化学 有机金属化学
- 协调化学 协调化学
- 催化剂是一种催化剂.
背景情况:
- 研究金属复合物与不和碳化合物的反应性.
- 了解氧化状态在化学转换中的作用.
- 探索潜在应用的可逆碳硫键形成.
研究的目的:
- 为了确定复合物的氧化状态对乙烯结合的影响.
- 量化碳 - 硫键形成反应的可逆性.
- 探索控制乙烯释放和吸收的潜力.
主要方法:
- 乙烯和复合体之间的反应的光谱分析 ([Re(DPPBT) ((3))) ((n+)).
- 结合常数和解离常数的电化学确定 (k{\displaystyle k} ,f{\displaystyle k} ,r{\displaystyle k} ,K).
- 用于产品结构特征的X射线晶体学.
主要成果:
- 中性 [Re(DPPBT) ((3) ] 没有与乙烯 (K ((1) = 1.9 x 10 ((-11) M ((-1)) 发生可检测反应.
- 氧化到[Re(DPPBT)(3)](+) 能够快速,可逆的乙烯结合 (K(2) = 4.0 M(-1)).
- 进一步的氧化对二解稳定了C-S键 (K(3) = 2.5 x 10(9) M(-1),产品通过X射线结晶学进行了特征.
结论:
- 复合物的氧化状态是控制乙烯结合可逆性的关键因素.
- 可调节的乙烯结合和释放可以通过调整复合物的电荷来实现.
- 该系统为需要控制气体吸收和释放的应用提供了潜力.
相关概念视频
Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.
Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene
The electrophilic addition of hydrogen halides such as HBr to alkenes and nonconjugated dienes gives a single product as per Markovnikov’s rule.


