通过添加连接体酸度常数来估计过渡金属化物和二复合物的酸度
1Department of Chemistry, University of Toronto , 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada.
Journal of the American Chemical Society
|January 14, 2014
概括
一个新的方程估计了各种溶剂中过渡金属化物和二复合物的酸度 (pKa). 这种方法有助于了解自然存在的和工业相关的金属复合物的酸度.
科学领域:
- 协调化学 协调化学
- 有机金属化学 有机金属化学
- 物理化学 物理化学
背景情况:
- 过渡金属化物和二复合物在催化和生物系统中至关重要.
- 准确的pKa值对于理解它们的反应性和稳定性至关重要.
- 现有的pKa测定方法可能是复杂且耗时的.
研究的目的:
- 为过渡金属化物和二复合物的pKa开发一种简单且广泛适用的预测方程.
- 提供一个工具,用于估计pKa值在四水夫和其他溶剂.
- 为了在各种应用中快速评估这些复合物的酸度.
主要方法:
- 使用一个简单的添加式方程进行定量结构-属性关系 (QSPR) 方法:pKa(THF) = AL + Ccharge + Cnd + Cd6.6.
- 确定了13种常见的配体类型的酸度常量 (AL),并与中性配体的勒弗电化学配体参数 (EL) 相对应.
- 针对复杂电荷 (Ccharge),过渡金属的周期行 (Cnd) 和八面体 d(6) 金属离子 (Cd6) 进行了校正.
主要成果:
- 该方程准确地估计了170多个文学pKa值,用于广泛的过渡金属复合物 (Cr到Ni,Mo,Ru到Pd,W到Pt).
- 该方法提供了良好的估计,在pKa范围0到50之间,标准偏差为3个pKa单位.
- 该方法还估计了无质子复合体形式的基强度.
结论:
- 开发的方程提供了一种简单可靠的方法来预测过渡金属化物和二复合物的酸度.
- 这种预测工具对于理解化,催化和能研究的应用非常有价值.
- 对于具有重或大咬角合连接体的复合体,注意到了偏差,这表明了未来改进的领域.
更多相关视频
09:45Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
9.6K
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
8.3K
相关概念视频
02:51Metal-Ligand Bonds
19.3K
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
19.3K
00:43Complexometric Titration: Ligands
2.5K
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...
2.5K
01:07Ladder Diagrams: Complexation Equilibria
736
Ladder diagrams are useful for evaluating equilibria involving metal-ligand complexes. The vertical scale of the ladder diagram represents the concentration of unreacted or free ligand, pL. The horizontal lines on the scale depict the log of stepwise formation constants for metal-ligand complexes and indicate the dominant species in all the regions.
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
736
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
997
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
997
03:45Formation of Complex Ions
18.8K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
18.8K
02:54Ions as Acids and Bases
22.8K
Salts with Acidic Ions
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:
22.8K