首页> 外文OA文献 >Synthesis, characterization and reactivity of heterobimetallic complexes (η5-C5R5)Ru(CO)(μ-dppm)M(CO)2 (η5-C5H5) (R = H, CH3; M = Mo, W). Interconversion of hydrogen/carbon dioxide and formic acid by these complexes
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Synthesis, characterization and reactivity of heterobimetallic complexes (η5-C5R5)Ru(CO)(μ-dppm)M(CO)2 (η5-C5H5) (R = H, CH3; M = Mo, W). Interconversion of hydrogen/carbon dioxide and formic acid by these complexes

机译:杂双金属配合物(η5-C5R5)Ru(CO)(μ-dppm)M(CO)2(η5-C5H5)(R = H,CH3; M = Mo,W)的合成,表征和反应性。这些配合物将氢/二氧化碳和甲酸相互转化

摘要

The heterobimetallic complexes [(η5-C5R5)Ru(CO)(μ-dppm) M(CO)2(η5-C5H5)] (M = Mo, W; R = H, CH3) (1-4) are prepared by metathetical reactions between (η5-C5R5)Ru(dppm)Cl and Na+[(η5-C5H5) M(CO)3]-. IR spectroscopic and X-ray structural studies show that each of these complexes contains a semi-bridging carbonyl ligand. The low activity of these complexes in catalytic CO2 hydrogenation to formic acid might be attributed to their non-facile reactions with H2 to yield the active dihydride species. The metal-metal bonds can be protonated to form the cationic complexes, which contain strong Ru-H-M bridges. The bridging hydrogen atom is weakly acidic since it can be removed by a strong base, and it protonates BPh4- to give BPh3 and benzene. It also reacts with the hydridic hydrogen of Et3SiH to yield H2. The bridging hydrogen, however, cannot be removed by hydride scavengers such as Ph3C+OTf- and Me3Si+OTf-. The sluggishness of the catalytic formic acid decomposition by 1-4 is attributable to the stability of the protonated bimetallic intermediate [(η5-C5R5)Ru(CO)(μ-dppm)(μ-H) M(CO)2(η5-C5H5)]+ HCOO- formed during the catalysis.
机译:杂双金属配合物[(η5-C5R5)Ru(CO)(μ-dppm)M(CO)2(η5-C5H5)](M = Mo,W; R = H,CH3)(1-4)的制备(η5-C5R5)Ru(dppm)Cl和Na + [(η5-C5H5)M(CO)3]-之间的对位反应。红外光谱和X射线结构研究表明,这些络合物均含有半桥羰基配体。这些配合物在催化CO2加氢成甲酸中的低活性可能归因于它们与H2的不易反应,无法生成活性二氢化物。可以使金属-金属键质子化以形成包含强Ru-H-M桥的阳离子配合物。桥连的氢原子是弱酸性的,因为它可以被强碱除去,并使BPh4-质子化,生成BPh3和苯。它还与Et3SiH的氢氢反应生成H2。但是,桥接氢不能被氢化物清除剂如Ph3C + OTf-和Me3Si + OTf-除去。 1-4分解甲酸的反应迟钝归因于质子化双金属中间体[(η5-C5R5)Ru(CO)(μ-dppm)(μ-H)M(CO)2(η5- C5H5)] + HCOO-在催化过程中形成。

著录项

  • 作者

    Man ML; Zhou Z; Ng SM; Lau CP;

  • 作者单位
  • 年度 2003
  • 总页数
  • 原文格式 PDF
  • 正文语种 eng
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