发现具有改进的选择性硫氧化催化性能的多金属氧酸盐基杂化物新家族：经典庚钼酸根阴离子与复杂阳离子之间的协同作用,Inorganic Chemistry

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发现具有改进的选择性硫氧化催化性能的多金属氧酸盐基杂化物新家族：经典庚钼酸根阴离子与复杂阳离子之间的协同作用
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2019-10-22 , DOI: 10.1021/acs.inorgchem.9b02601
Yin Zhang , Wei-Dong Yu , Bin Li , Zheng-Fan Chen , Jun Yan

一系列功能性阳离子调节的基于异聚钼酸盐的有机-无机杂化化合物，Na ₂ H ₂ [Mo ₄ O ₁₂（C ₈ H ₁₇ O ₅ N）₂ ]·10H ₂ O（1），Na ₂ [M（Bis -tris）（H ₂ O）] ₂ [Mo ₇ O ₂₄ ]·10H ₂ O [M = Cu，2 ; 镍，3 ; Co，4 ; 锌，5 ; Bis-tris = 2,2-Bis（羟甲基）-2,2'，2”-亚硝基三乙醇]和（NH ₄）₂合成了[M（Bis-tris）（H ₂ O）] ₂ [Mo ₇ O ₂₄ ]·6H ₂ O（M = Zn，6 ; Cu，7），并对其进行了表征，以进行先进的分子催化剂设计。化合物1是共价键合的加合物，其自组装过程可通过电喷雾电离质谱（ESI-MS）进行探测。化合物2 - 7是多金属氧酸盐（POM）含七钼酸铵经典阴离子和配合物阳离子与双-三配位体为基础的杂合体。所有这些化合物对选择性硫化物氧化均显示出显着的催化作用。据我们所知，化合物5在报告的具有常见的易于合成的小分子POM簇的杂化材料中，具有最佳的催化活性，并且还具有出色的可靠性。催化作用的结论是从以下结果得出的：基于锌的化合物比其他含过渡金属的化合物具有更好的催化作用，并且由Na ⁺构造的化合物比由NH ₄⁺构造的化合物具有更高的催化活性。。机理研究表明，催化性能的提高是由经典的七钼酸根阴离子与复杂阳离子之间的协同作用引起的。ESI-MS数据和UV-vis光谱表明，POM阴离子可在催化反应过程中形成中间的过氧钼单元。此外，底物硫代茴香醚与复杂阳离子的结合通过NMR实验和UV-vis光谱进行了表征。因此，提出了一种新的阴离子和阳离子协同机理，其中活化的硫代苯甲醚被用作亲核试剂攻击过氧钼键，这为可靠的基于POM的催化剂的设计提供了新的策略。

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Discovery of a New Family of Polyoxometalate-Based Hybrids with Improved Catalytic Performances for Selective Sulfoxidation: The Synergy between Classic Heptamolybdate Anions and Complex Cations

A series of functional cation-regulated isopolymolybdate-based organic–inorganic hybrid compounds, Na₂H₂[Mo₄O₁₂(C₈H₁₇O₅N)₂]·10H₂O (1), Na₂[M(Bis-tris)(H₂O)]₂[Mo₇O₂₄]·10H₂O [M = Cu, 2; Ni, 3; Co, 4; Zn, 5; Bis-tris = 2,2-Bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol], and (NH₄)₂[M(Bis-tris)(H₂O)]₂[Mo₇O₂₄]·6H₂O (M = Zn, 6; Cu, 7), were synthesized and characterized toward advanced molecular catalyst design. Compound 1 is a covalently bonded adduct, and its self-assembly process can be probed by electrospray ionization mass spectrometry (ESI-MS). Compounds 2–7 are polyoxometalate (POM)-based hybrids containing classic heptamolybdate anions and complex cations with Bis-tris ligands. All of these compounds showed remarkable catalytic effects for selective sulfide oxidation. To the best of our knowledge, compound 5 presents the best catalytic activity so far among the reported hybrid materials with common easily synthesized small-molecule POM clusters and also exhibits outstanding reliability. The conclusion of the catalytic effect is drawn from the results that Zn-based compounds have better catalytic effects than other transition-metal-containing compounds and the compound constructed by Na⁺ has higher catalytic activity than that constructed by NH₄⁺. The mechanism studies show that the improvements of the catalytic performance are caused by the synergy between classic heptamolybdate anions and complex cations. ESI-MS data and UV–vis spectra revealed that the POM anions can form intermediate peroxomolybdenum units during catalytic reaction. Further, the combination of the substrate thioanisole with complex cations was characterized by NMR experiments and UV–vis spectra. Thus, a new synergistic mechanism of anions and cations is proposed in which the activated thioanisole is used as a nucleophile to attack the peroxomolybdenum bonds, and this provides a new strategy in the design of reliable POM-based catalysts.

更新日期：2019-10-23

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