Gas-phase and solution-phase homolytic bond dissociation energies of H-N+ bonds ill the conjugate acids of nitrogen bases
Gas-phase and solution-phase homolytic bond dissociation energies of H-N+ bonds ill the conjugate acids of nitrogen bases
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DOI：
10.1021/jo950933r
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发表时间：
1996-07-12
影响因子：
3.6
通讯作者：
Bordwell, FG
中科院分区：
文献类型：
--
作者：
Liu, WZ;Bordwell, FG
测定了19种氮碱（简称为B: 6种伯胺、5种仲胺、2种叔胺、3种苯胺、吡啶、喹啉和1,4-重氮双环[2,2,2]-辛烷）在二甲基亚砜（DMSO）和乙腈（AN）中的氧化电位，即E(ox)(B)值。将这些E(ox)(B)值与相应的酸（PKHB+）在DMSO和/或AN中的酸度值结合使用公式：BDE(HB)(+) = 1.37pK(HB)(+) + 23.1 E(ox)(B) + C （C在AN中等于59.5 kcal/mol，在DMSO中等于73.3 kcal/mol）给出了H-B+键的溶液均溶键解离能的估计。根据更新后的质子亲和势（PA）和绝热电离势（aIP），利用公式BDE-(HB+)(g) = PA + aIP - 314 kcal/mol，估算了H-B+键的气相BDE值。在AN中估计的BDE(HB)（+）值比相应的气相BDE(HB+)(g)值高5-11 kcal/mol。这些在溶液中的键强化效应被解释为由于HB+阳离子的溶剂化能大于B——。激进的阳离子。
The oxidation potentials of 19 nitrogen bases (abbreviated as B: six primary amines, five secondary amines, two tertiary amines, three anilines, pyridine, quinuclidine, and 1,4-diazabicyclo[2,2,2]-octane), i.e., E(ox)(B) values in dimethyl sulfoxide (DMSO) and/or acetonitrile (AN), have been measured. Combination of these E(ox)(B) values with the acidity values of the corresponding acids (PKHB+) in DMSO and/or AN using the equation: BDE(HB)(+) = 1.37pK(HB)(+) + 23.1 E(ox)(B) + C (C equals 59.5 kcal/mol in AN and 73.3 kcal/mol in DMSO) gave estimates of solution phase homolytic bond dissociation energies of H-B+ bonds. Gas-phase BDE values of H-B+ bonds were estimated from updated proton affinities (PA) and adiabatic ionization potentials (aIP) using the equation, BDE-(HB+)(g) = PA + aIP - 314 kcal/mol. The BDE(HB)(+) values estimated in AN were found to be 5-11 kcal/mol higher than the corresponding gas phase BDE(HB+)(g) values. These bond-strengthening effects in solution are interpreted as being due to the greater solvation energy of the HB+ cation than that of the B--. radical cation.