一个自由的,三坐标的酸
Joseph B Lambert1, Lijun Lin, Shahar Keinan
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|June 6, 2003
概括
这项研究揭示了一种稳定的,自由的三坐标离子,Tris ((2,4,6-triisopropylphenyl) stannylium,由X射线和DFT方法证实. 研究澄清了其独特的结构和结合,推进了有机蛋白化学.
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
- 固态化学 固态化学
背景情况:
- 三坐标离子是罕见的和高度反应的物种.
- 了解它们的结构和结合是开发新合成方法的关键.
- 之前的研究往往涉及过渡性或溶解酸盐.
研究的目的:
- 合成和表征一个稳定的,自由的三坐标离子.
- 为了阐明Tris ((2,4,6-triisopropylphenyl) stannylium电离子的结构和电子特性.
- 为了研究潜在的杂质相互作用,并确认质子的电子结构.
主要方法:
- 单晶X射线衍射以确定精确的原子排列.
- 密度函数理论 (DFT) 计算用于结构和电子分析.
- 核磁共振 (NMR) 光谱,特别是119Sn NMR,用于探测锡环境.
主要成果:
- X射线结构证实了一个自由的三坐标离子,没有溶剂或反离子协调.
- DFT的计算支持了观察到的结构,并排除了异基和锡原子之间有毒的结合.
- 计算的119Sn化学转移与实验值非常一致,验证了电子结构.
结论:
- 三二四六二二二四二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二二
- 庞大的三甲基组有效地屏蔽了锡中心,防止不必要的协调.
- 这项工作为高价位有机化合物的基本化学提供了宝贵的见解.
相关概念视频
01:24pH
The potential of hydrogen (pH) is a measure of the acidity or basicity of a water-based solution determined by the concentration of hydronium ions (H3O+). In one liter of pure water at neutral pH, there are 1×10−7 moles of hydronium ions. However, the extensive range of hydronium ion concentrations present in water-based solutions makes measuring pH in moles cumbersome. Therefore, a pH scale was developed to convert moles of hydronium ions into the negative logarithm of the hydronium ion...
03:38Polyprotic Acids
Acids are classified by the number of protons per molecule that they can give up in a reaction. Acids such as HCl, HNO3, and HCN that contain one ionizable hydrogen atom in each molecule are called monoprotic acids. Their reactions with water are:
03:05Acid Strength and Molecular Structure
Binary Acids and Bases
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
01:24pH
The potential of hydrogen (pH) is a measure of the acidity or basicity of a water-based solution determined by the concentration of hydronium ions (H3O+). In one liter of pure water at neutral pH, there are 1×10−7 moles of hydronium ions. However, the extensive range of hydronium ion concentrations present in water-based solutions makes measuring pH in moles cumbersome. Therefore, a pH scale was developed to convert moles of hydronium ions into the negative logarithm of the hydronium ion...
01:10Acid–Base Equilibria: Activity-Based Definition of pH
For an ideal solution, the pH is defined as the negative logarithm of the hydrogen ion concentration. For a non-ideal solution, an accurate measurement of the pH must consider the negative logarithm of the hydrogen ion activity rather than concentration. In such a solution, the pH can be more accurately defined as the negative logarithm of a product of the hydrogen ion concentration and its activity coefficient.
In solutions of very low ionic strength—for example, pure water—the activity...
In solutions of very low ionic strength—for example, pure water—the activity...
01:19Mixtures of Acids
The pH of a solution containing an acid can be determined using its acid dissociation constant and initial concentration. If a solution contains two different acids, then its pH can be determined using one of several methods depending on the relative strength of the acids and their dissociation constants.
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...