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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Ruthenium substituted Keggin type polyoxomolybdates: synthesis, characterization and use as bifunctional catalysts for the epoxidation of alkenes by molecular oxygen
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Ruthenium substituted Keggin type polyoxomolybdates: synthesis, characterization and use as bifunctional catalysts for the epoxidation of alkenes by molecular oxygen

机译：钌取代的Keggin型聚氧钼酸酯：合成，表征和用作双官能催化剂，用于分子氧环烯烃的环氧化

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摘要

The ruthenium substituted polyoxomolybdate of the Keggin structure, Q(4)PRu(III)(H2O)Mo11O39 (Q = n-Bu4N), has been synthesized and characterized. The IR spectra show that this compound is isostructural with the known manganese and cobalt analogs. The cyclic voltammogram showed similar redox potentials and the UV-vis spectra showed similar energies for the d-d transitions compared to the corresponding tungstate, Q(4)PRu(III)(H2O)W11O39. The catalytic activity of the molybdate ver;sus tungstate in reactions with molecular oxygen was, however, significantly different. IR and P-31 NMR evidence indicated that treatment of Q(4)PRu(III)(H2O)Mo11O39 with oxygen showed no structural changes whereas, for Q(4)PRu(III)(H2O)W11O39, a clear change was observed. This finding probably explains the lack of catalytic activity for the latter in the cooxidation of cumene and 1-octene to cumyl alcohol and 1-octene oxide. For the molybdenum compound, this reaction took place by a kinetic balance of ruthenium metal-catalyzed autooxidation of cumene to cumene hydroperoxide and the molybdenum catalyzed oxygen transfer from cumene hydroperoxide to 1-octene to yield the products. High catalyst loading led to reaction inhibition whereas low loading and excess cumene led to increased autooxidation. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 45]
机译：合成并表征了Keggin结构的钌取代的聚氧钼酸盐Q（4）PRu（III）（H2O）Mo11O39（Q = n-Bu4N）。红外光谱表明该化合物与已知的锰和钴类似物是同构的。与相应的钨酸盐Q（4）PRu（III）（H2O）W11O39相比，循环伏安图显示了相似的氧化还原电位，UV-vis光谱显示了d-d跃迁的相似能量。然而，钼酸对钨酸盐在与分子氧反应中的催化活性显着不同。 IR和P-31 NMR证据表明，用氧气处理Q（4）PRu（III）（H2O）Mo11O39没有结构变化，而对于Q（4）PRu（III）（H2O）W11O39，观察到明显变化。该发现可能解释了后者在枯烯和1-辛烯共氧化成枯基醇和1-辛烯氧化物中缺乏催化活性的原因。对于钼化合物，该反应通过钌金属催化的枯烯自氧化为异丙苯氢过氧化物的动力学平衡和钼催化的氧从枯烯氢过氧化物向1-辛烯的转移而发生。高催化剂负载量导致反应抑制，而低负载量和过量的异丙基苯导致自氧化增加。 （C）1998 Elsevier ScienceLtd。保留所有权利。 [参考：45]

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