Controlled Copper-Mediated Chlorination of Phenol Rings under Mild Conditions

The very unusual case of copper-mediated chlorination of phenol rings under mild conditions at room temperature
is reported. Reaction of the ligand 1,7-bis(2-hydroxyphenyl)-2,6-diaza-4-hydroxylheptane (H3L1) with CuCl2 in
acetonitrile leads to either the formation of a tetranuclear copper(II) complex [Cu4(HL3)2(μ-Cl)2Cl2](CH3CN) (1) or
a linear trinuclear complex [Cu3(HL1)2Cl2(CH3CN)2](CH3CN)2 (2), depending on the reaction conditions. Both
compounds have been fully characterized, including the determination of their 3D structures by X-ray diffraction.
The unprecedented tetranuclear compound 1 is constituted of a dichlorido-bridged dimer of di-μ-phenoxido-dinuclear
species, whereas the trinuclear complex 2 presents a linear array of copper(II) ions, held together through di-μ-phenoxido bridges of the central and external ions. The magnetic susceptibility of the two compounds was investigated,
revealing either very strong (J < −500 cm-1) or strong (J value around −370(1) cm-1) antiferromagnetic dominant
interactions among the CuII ions for 1 and 2, respectively. The tetranuclear complex 1 is obtained, under dry
conditions, through the in situ formation of ligand HL3 (H3L3 = 1,7-bis(2-hydroxy-5-chlorophenyl)-2,6-diaza-4-hydroxylheptane) by oxidative chlorination of (HL1)2-. In the presence of traces of water, 1 is partially hydroxylated
at the ortho position of one of the phenyl rings. The use of trimethylorthoformate as the dehydrating agent prevents
the formation of hydroxylated ligands. Several partly chlorinated/hydroxylated products (identified as H3L2) have
also been obtained through slight variations of the synthetic procedures (presence or absence of water and/or
triethylamine in the reaction mixtures). These partially chlorinated and/or hydroxylated coordination species are
mutually isomorphous to either 1 or 2. Several “modified” ligands have been isolated and characterized by 1H NMR
and MS, after reaction with sodium sulfide of the complexes formed.

报道了一种极为罕见的温和条件下室温下铜催化的酚环氯化反应。配体1,7-双(2-羟基苯基)-2,6-二氮-4-羟基庚烷（H3L1）与CuCl2在乙腈中的反应，根据反应条件，可生成四核铜(II)配合物[Cu4(HL3)2(μ-Cl)2Cl2](CH3CN)（1）或线性三核配合物[Cu3(HL1)2Cl2(CH3CN)2](CH3CN)2（2）。这两种化合物均已进行了全面表征，包括通过X射线衍射确定其三维结构。前所未有的四核化合物1由二氯桥连的二核二μ-苯氧基物种的二聚体构成，而三核配合物2则呈现铜(II)离子的线性阵列，通过中心与外围离子的二μ-苯氧基桥连接在一起。对这两种化合物的磁化率进行了研究，发现1和2中的CuII离子分别表现出非常强的（J < −500 cm-1）或强的（J值约为−370(1) cm-1）反铁磁主导相互作用。在干燥条件下，通过现场形成配体HL3（H3L3 = 1,7-双(2-羟基-5-氯苯基)-2,6-二氮-4-羟基庚烷）并通过氧化氯化(HL1)2-获得四核配合物1。在水痕存在的情况下，1在苯环的邻位部分发生部分羟基化。使用三甲基甲酰甲酸酯作为脱水剂，可以防止羟基化配体的形成。通过合成方法的微小变化（反应混合物中是否存在水和/或三乙胺），也获得了几种部分氯化/羟基化的产物（鉴定为H3L2）。这些部分氯化/羟基化的配位物种与1或2相互同晶。通过与形成的配合物中的硫化钠反应，分离并表征了多种“改性”配体，其方法为1H NMR和MS。