Dramatic improvements of well-defined silica supported mo-based olefin metathesis catalysts by tuning the N-containing ligands
Dramatic improvements of well-defined silica supported mo-based olefin metathesis catalysts by tuning the N-containing ligands
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DOI：
10.1021/ja073095e
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发表时间：
2007-07-11
影响因子：
15
通讯作者：
Schrock, Richard R.
中科院分区：
文献类型：
--
作者：
Blanc, Frederic;Berthoud, Romain;Schrock, Richard R.
质量平衡分析、红外光谱和核磁共振谱表明，在SiO_2-(700)上接枝[Mo(NAR)(CHCMe2R1)(NR2)(2)]得到了主要的表面物种[(SiO)Mo(NAR)(CHCMe2R1)(NR2)]和[(SiO)Mo(NAR)(CH2CMe2R1)(NR2)(2)]。二氧化硅表面的硅氧基取代了一个氨基，大大提高了钼络合物在烯烃歧化反应中的活性，调节酰亚胺配体可以使反应活性提高至少一个数量级，从而使丙烯歧化反应的总转化率达到231 000。此外，只需0.02%的催化剂，油酸乙酯也可以在8h内转化为热力学平衡混合物。
Grafting [Mo(NAr)(CHCMe2R1)(NR2)(2)] on SiO2-(700) gives [(SiO)Mo(NAr)(CHCMe2R1)(NR2)] as a major surface species along with [(SiO)Mo(NAr)(CH2CMe2R1)(NR2)(2)] according to mass balance analysis, IR and NMR spectroscopies. The replacement of one amido group by a siloxy group from the surface of silica dramatically increased the activity of the Mo complex in olefin metathesis, and tuning the imido ligands allows the reactivity to be increased by at least one order of magnitude so that an overall turnover of 231 000 can be achieved in the metathesis of propene. Additionally, ethyl oleate can also be converted into a thermodynamic equilibrated mixture in 8 h with only 0.02% of catalyst.