Ab initio unrestricted Hartree−Fock calculations with a 6-31G* basis set were performed on 2,6-dimethylphenol (DMP or monomer) and 4-(2,6-dimethylphenoxy)-2,6-dimethylphenol (dimer) to gain more insight into the mechanism of the copper-catalyzed oxidative phenol coupling reaction. Atomic charges were determined for the phenol, phenoxyl radical, phenolate anion and phenoxonium cation (both the singlet and triplet state) of both species. Calculations for the monomer show that the only aromatic carbon atom bearing a partial positive atomic charge is the para carbon of the cation in the singlet state. In the case of the dimer, the presence of a p-phenoxy substituent results in a partial positive charge for the para carbon of the first aromatic ring in all states, but this charge is significantly higher for the singlet cation. In the singlet cationic state, the para carbon of the first aromatic ring is therefore the site most susceptible to nucleophilic aromatic substitution. This result strongly supports a pr...

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Ab InitioCalculations on 2,6-Dimethylphenol and 4-(2,6-Dimethylphenoxy)-2,6-二甲基苯酚。苯氧鎓阳离子在铜催化氧化苯酚偶联反应中起重要作用的证据

使用 6-31G* 基组对 2,6-二甲基苯酚（DMP 或单体）和 4-（2,6-二甲基苯氧基）-2,6-二甲基苯酚（二聚体）进行从头算不受限制的 Hartree-Fock 计算以获得更多深入了解铜催化氧化苯酚偶联反应的机理。确定了两种物质的苯酚、苯氧基自由基、苯酚阴离子和苯氧鎓阳离子（单线态和三线态）的原子电荷。单体的计算表明，唯一带有部分正原子电荷的芳族碳原子是单线态阳离子的对位碳。在二聚体的情况下，对苯氧基取代基的存在导致所有状态下第一个芳环的对位碳带部分正电荷，但对于单线态阳离子，这种电荷明显更高。因此，在单线态阳离子状态下，第一个芳环的对位碳是最容易发生亲核芳族取代的位点。这一结果强烈支持公...