High metathesis activity ruthenium and osmium metal carbene complexes

#This invention relates to highly active and stable ruthenium and osmium metal carbene complex compounds, their synthesis and use as catalysts for olefin metathesis reactions.

#Transition-metal catalyzed C—C bond formation via olefin metathesis is of considerable interest and synthetic utility. Initial studies in this area were based on catalytically active mixtures consisting of transition-metal chlorides, oxides or oxychlorides, cocatalysts such as EtAlCl2 or R4Sn, and promoters including O2, EtOH or PhOH. For example, WCl6/EtAlCl2/EtOH 1:4:1. These systems catalyze olefin metathesis reactions, however their catalytic centers are ill-defined and systematic control of their catalytic activity is not possible.

#Recent efforts have been directed towards the development of well-defined metathesis active catalysts based-on transition metal complexes. The results of research efforts during the past two decades have enabled an in-depth understanding of the olefin metathesis reaction as catalyzed by early transition metal complexes. In contrast, the nature of the intermediates and the reaction mechanism for Group VIII transition metal catalysts have remained elusive. In particular, the oxidation states and ligation of the ruthenium and osmium metathesis intermediates are not known.

#The invention will be better understood by reference to the appended figures wherein:

#FIGS. 1A and 1B are representative kinetic plots for acyclic metathesis of 1-hexene with RuCl2(═CHPh)(PCy3)2 (complex 10) at 0° C.; and

#FIG. 2 is an ORTEP plot of RuCl2(═CH-p-C6H4Cl)(PCy3)2 (complex 15).

#The abbreviations Me, Ph, iPr or i-Pr, Cy, Cp, n-Bu, and THF refer to methyl, phenyl, isopropyl, cyclohexyl, cyclopentyl, n-butyl, and tetrahydrofuran, respectively.

#While previous investigations have explored the influence of the neutral electron donor and anionic ligands (i.e. L, L1, X, and X1) on the stability and utility of the ruthenium and osmium carbene complexes, the effect of variation of the alkylidene moieties (R and R1) had not been studied. By studying the effect of these substituents, it has been discovered that ruthenium and osmium complexes containing the specific alkylidene moieties of the present invention have unexpectedly high initiation rates compared to the vinyl alkylidene complexes previously described. Quantitative data is included below that demonstrates that the initiation rates of the complexes of the present invention are approximately a thousand times higher than the initiation rates of the corresponding vinyl alkylidene complexes. In addition to having unexpectedly high initiation rates, the complexes of the present invention are stable in the presence of a variety of functional groups and have high metathesis activity allowing them to catalyze a variety of metathesis reactions including metathesis reactions involving acyclic and unstrained cyclic olefins.

#The compounds of the present invention are ruthenium and osmium alkylidene complexes of the general formula