Decomposition of ruthenium olefin metathesis catalysts
Decomposition of ruthenium olefin metathesis catalysts
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DOI：
10.1021/ja0713577
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发表时间：
2007-06-27
影响因子：
15
通讯作者：
Grubbs, Robert H.
中科院分区：
文献类型：
--
作者：
Hong, Soon Hyeok;Wenzel, Anna G.;Grubbs, Robert H.
以亚甲基为模型络合物，考察了一系列Ru复分解催化剂的分解反应。所有含膦亚甲基络合物均分解生成甲基膦盐，其分解过程符合一级动力学。这些盐在高转化率下的形成，再加上观察到的该反应的动力学行为，表明主要的分解途径涉及解离的膦对亚甲基碳的亲核攻击。这一机理也与在以乙烯为模型烯烃底物的情况下观察到的分解一致。无膦催化剂(H(2)IMES)(Cl)(2)Ruch(2-C6H4-O-i-Pr)(H(2)IMES=1，3-二甲苯基-4，5-二氢咪唑-2-亚甲基)与乙烯的分解生成不明的氢化钌物种。本文还报道了在合成高度不稳定的吡啶亚甲基配合物(H(2)IMES)(吡啶)(2)(Cl)(2)RuCH2的过程中生成的新型Ru配合物(H(2)IMES)(吡啶)(3)(Cl)(2)Ru。
The decomposition of a series of ruthenium metathesis catalysts has been examined using methylidene species as model complexes. All of the phosphine-containing methylidene complexes decomposed to generate methylphosphonium salts, and their decomposition routes followed first-order kinetics. The formation of these salts in high conversion, coupled with the observed kinetic behavior for this reaction, suggests that the major decomposition pathway involves nucleophilic attack of a dissociated phosphine on the methylidene carbon. This mechanism also is consistent with decomposition observed in the presence of ethylene as a model olefin substrate. The decomposition of phosphine-free catalyst (H(2)IMes)(Cl)(2)RuCH(2-C6H4-O-i-Pr) (H(2)IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) with ethylene was found to generate unidentified ruthenium hydride species. The novel ruthenium complex (H(2)IMes)(pyridine)(3)(Cl)(2)Ru, which was generated during the synthetic attempts to prepare the highly unstable pyridine-based methylidene complex (H(2)IMes)(pyridine)(2)(Cl)(2)RuCH2, is also reported.