对C-C和C-H键激活的固体和电子要求的比较. 化与非化案例
B Rybtchinski1, S Oevers, M Montag
1Department of Organic Chemistry, Chemical Services Unit, Weizmann Institute of Science, 76100 Rehovot, Israel.
Journal of the American Chemical Society
|September 13, 2001
概括
这项研究表明C-H和C-C键激活使用一种新型的PCO配体与前体. 化在C-C键激活中起着关键作用,两种激活类型的电子要求相似.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 反应机制研究 反应机制研究
背景情况:
- 在有机金属化学中,C-H和C-C键激活是基本的转化.
- 复合物因其在键激活反应中的催化活性而被广泛研究.
- 了解连接物结构和电子/固态因子的作用对于设计高效的催化剂至关重要.
研究的目的:
- 为了研究C-H和C-C键激活反应,使用一种新型的PCO配体与前体.
- 描述由此产生的复合物,并阐明反应机制.
- 为了比较C-H与C-C键激活的电子和固体要求.
主要方法:
- 一个新的PCO配体与一个阴离子前体的反应 ([Rh(coe) (((2) ((solv) ((n) ((() ]BF(4)).
- 反应产物的光谱表征 (NMR,X射线晶体学).
- 使用B3LYP和mPW1K函数的双层ONIOM模型进行计算研究.
主要成果:
- 在室温下,在各种溶剂中观察到C-H键激活.
- 形成了两种类型的产品,在甲氧臂协调上有所不同.
- 在加热或溶剂蒸发时发生了C-C键激活,产生了一个方形金字塔形的罗复合体.
- 计算研究表明类似的电子要求,但对C-H和C-C激活有不同的硬质要求,化对C-C激活很重要.
结论:
- 这种新型的PCO连接体促进了C-H和C-C键的激活,并使用了前体.
- 化是C-C键激活的一个重要因素,影响反应途径.
- 该研究提供了对催化键激活的机械方面的见解,突出了电子和硬质效应的相互作用.
相关概念视频
02:37Types of Chemical Bonds
Chemical bonding theories were pioneered by American chemist Gilbert N. Lewis. He developed a model called the Lewis model to explain the type and formation of different bonds. Chemical bonding is central to chemistry; it explains how atoms or ions bond together to form molecules. It explains why some bonds are strong and others are weak, or why one carbon bonds with two oxygens and not three; why water is H2O and not H4O.
02:46Covalent Bonding and Lewis Structures
Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual attraction of atoms for a “shared” pair of electrons.
03:37Molecular Shape and Polarity
Dipole Moment of a Molecule
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
01:26Photochemical 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
02:37Types of Chemical Bonds
Chemical bonding theories were pioneered by American chemist Gilbert N. Lewis. He developed a model called the Lewis model to explain the type and formation of different bonds. Chemical bonding is central to chemistry; it explains how atoms or ions bond together to form molecules. It explains why some bonds are strong and others are weak, or why one carbon bonds with two oxygens and not three; why water is H2O and not H4O.