Love Jennifer A, Sanford Melanie S, Day Michael W, Grubbs Robert H
Arnold and Mabel Beckman Laboratories for Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
J Am Chem Soc. 2003 Aug 20;125(33):10103-9. doi: 10.1021/ja027472t.
A series of ruthenium olefin metathesis catalysts of the general structure (H(2)IMes)(PR(3))(Cl)(2)Ru=CHPh (H(2)IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) have been prepared; these complexes are readily accessible in two steps from commercially available (H(2)IMes)(PCy(3))(Cl)(2)Ru=CHPh. Their phosphine dissociation rate constants (k(1)), relative rates of phosphine reassociation, and relative reaction rates in ring-opening metathesis polymerization (ROMP) and ring-closing metathesis (RCM) have been investigated. The rates of phosphine dissociation (initiation) from these complexes increase with decreasing phosphine donor strength. Complexes containing a triarylphosphine exhibit dramatically improved initiation relative to (H(2)IMes)(PCy(3))(Cl)(2)Ru=CHPh. Conversely, phosphine reassociation shows no direct correlation with phosphine electronics. In general, increased phosphine dissociation leads to faster olefin metathesis reaction rates, which is of direct significance to both organic and polymer metathesis processes.
已制备出一系列具有通式结构(H(2)IMes)(PR(3))(Cl)(2)Ru=CHPh的钌烯烃复分解催化剂（H(2)IMes = 1,3 - 二甲基苯基 - 4,5 - 二氢咪唑 - 2 - 亚基）；这些配合物可通过两步法从市售的(H(2)IMes)(PCy(3))(Cl)(2)Ru=CHPh轻松制得。研究了它们的膦解离速率常数(k(1))、膦重新结合的相对速率以及在开环复分解聚合(ROMP)和闭环复分解(RCM)中的相对反应速率。这些配合物的膦解离（引发）速率随膦供体强度的降低而增加。相对于(H(2)IMes)(PCy(3))(Cl)(2)Ru=CHPh，含有三芳基膦的配合物表现出显著改善的引发效果。相反，膦重新结合与膦电子学没有直接关联。一般来说，膦解离增加会导致烯烃复分解反应速率加快，这对有机和聚合物复分解过程都具有直接意义。
