立体电子效应和西格玛键的高结合性受体能力的一般趋势
Igor V Alabugin1, Tarek A Zeidan
1Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA. alabugin@chem.fsu.edu
Journal of the American Chemical Society
|March 21, 2002
概括
这项研究揭示了碳主要组元素键的西格玛受体特性趋势. 受体能力受到电子负性和轨道能量的影响,在设计分子二极管方面有应用.
科学领域:
- 计算化学是一种计算化学.
- 有机化学 有机化学
- 量子化学是一种量子化学.
背景情况:
- 了解化学键中的立体电子效应对于预测分子性质至关重要.
- 碳主要组元素 (C-X) 键表现出不同的西格玛受体特性.
- 以前的研究已经探讨了替代效应,但需要进行系统的趋势分析.
研究的目的:
- 系统地调查C-X债券的西格玛接受器属性的一般趋势.
- 为了将这些属性与替代物特性和轨道能量相关联.
- 探索分子设计中的潜在应用,例如分子二极管.
主要方法:
- 对西格玛接受器属性的系统计算研究.
- 对主要组元素 (IVa-IIa) 跨时期和组的趋势分析.
- 在单替代乙和乙烯中检查C-X键.
主要成果:
- 西格玛接受者能力在一个时期结束时增加,并在一个组下降.
- 电子阴性主要控制周期的趋势,而轨道能量则在组中占主导地位.
- 在乙烯中,由于轨道重叠增加,电子阴性变得更加显著,导致复杂的,依赖于调整器的行为.
- 在C-X键 (例如,C-素) 中观察到的异型性质表明了单向电子导电性的潜力.
结论:
- 建立了sigma接受器属性的一般趋势,提供了定性理解.
- 电子阴性和轨道能量起着关键的,有时是竞争性的作用.
- 可利用 anisotropic sigma 接受器的特性来设计分子二极管.
- 过度结合效应对结构变化非常敏感,强调需要理论方法.
相关概念视频
02:54Trends in Lattice Energy: Ion Size and Charge
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
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...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:27The Debye–Hückel Theory of Electrolyte Solutions
The Debye–Hückel theory, established by Peter Debye and Erich Hückel in 1923, is a fundamental concept in physical chemistry. It provides an understanding of the behavior of strong electrolytes in solution, particularly explaining their deviations from ideal behavior.The theory is based on Coulombic interactions (the attraction or repulsion between charged particles) between ions in solution. In an ionic solution, oppositely charged ions tend to attract each other. This means that cations...
01:23Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...