The selective oxidation of thioethers is among the most straightforward and common methods to obtain the synthetic intermediates sulfoxides for application in chemical industry, medicinal chemistry and biology. In this study, we prepared four hybrid compounds, i.e. Cs₄[M(H₂O)₄][PMo₆O₂₁(PABA)₃]₂·nH₂O 1–4 (M = Co, Mn, Ni, Zn; PABA = p-aminobenzoic acid), based on carboxylic acid-modified polyoxomolybdates and metal cations with wonderful catalytic performance for the selective oxidation of thioethers. The compounds 1–4 comprise PABA ligand-modified polyoxomolybdates [PMo₆O₂₁(PABA)₃]³⁻ as building units and the Co²⁺/Mn²⁺/Ni²⁺/Zn²⁺ cations as linkers to generate novel dimeric architectures. Using compound 1 as a pre-catalyst, methyl phenyl sulfides were nearly entirely converted to sulfoxides with the selectivity of 98% at room temperature within 20 minutes. Satisfactory catalytic effects were also observed in the selective oxidation of various phenyl sulfides with substituent groups; in particular, another typical thioether, i.e. the chemical warfare agent simulant 2-chloroethyl ethyl sulfide (CEES), could be completely degraded to nontoxic 2-chloroethyl ethyl sulfoxide (CEESO) with the selectivity of 99% within 12 minutes at room temperature. These pre-catalysts could be recycled at least 10 times by simple filtration with a negligible decrease in conversion and selectivity.

中文翻译：

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有机配体改性的聚氧钼酸酯催化各种硫醚的高效氧化†

硫醚的选择性氧化是获得用于化学工业，药物化学和生物学的合成中间体亚砜的最直接，最常用的方法之一。在这项研究中，我们制备了四种杂化化合物，即Cs ₄ [M（H ₂ O）₄ ] [PMo ₆ O ₂₁（PABA）₃ ] ₂ · n H ₂ O 1-4（M = Co，Mn，Ni， Zn； PABA =对氨基苯甲酸），基于羧酸改性的聚氧钼酸酯和金属阳离子，具有出色的催化性能，可选择性氧化硫醚。化合物1-4包含PABA配体改性的聚氧钼酸酯[PMo ₆ O ₂₁（PABA）₃ ] ^3-作为构建单元，并包含Co ²⁺ / Mn ²⁺ / Ni ²⁺ / Zn ²⁺阳离子作为连接基，以生成新颖的二聚体结构。使用化合物1作为前催化剂，甲基苯基硫化物在室温下在20分钟内几乎完全转化为亚砜，其选择性为98％。在各种带有取代基的苯基硫化物的选择性氧化中也观察到令人满意的催化作用。特别是另一种典型的硫醚，即化学战剂模拟物2-氯乙基乙基亚砜（CEES）在室温下12分钟内可被完全降解为无毒的2-氯乙基乙基亚砜（CEESO），选择性为99％。这些预催化剂可以通过简单的过滤循环至少10次，转化率和选择性的降低可忽略不计。