Multicoordinated metal complexes for use in metathesis reactions

Abstract

Improved catalysts useful in alkyne or olefin metathesis are made by bringing into contact a multi-coordinated metal complex comprising a multidentate Schiff base ligand, and one or more other ligands, with a selected activating compound under conditions such that at least partial cleavage of a bond between the metal and the multidentate Schiff base ligand of said metal complex occurs.

Description

[0001] This application claims priority from U.S. provisional application No. 60 / 710,073, filed Aug. 22, 2005 and from British patent application serial number GB 0517137.6 filed Aug. 22, 2005; the disclosures of each are hereby incorporated by reference.[0002] The present invention relates to multicoordinated metal complexes which are useful as catalyst components, either alone or in combination with co-catalysts or initiators, in a wide variety of organic synthesis reactions including the metathesis of unsaturated compounds such as olefins and alkynes. [0003] The present invention also relates to methods for making said multicoordinated metal complexes and to novel intermediates involved in such methods. More particularly, the present invention relates to multicoordinated complexes of metals such as but not limited to ruthenium wherein said complexes comprise a modified Schiff base ligand, as well as methods for making the same and the use of such multicoordinated metal complexes ...

AI Technical Summary

Benefits of technology

[0084] In this specific embodiment, at least partial cleavage of a bond between the metal and the multidentate Schiff base ligand of said multi-coordinated metal complex occurs like in the absence of the further reactant (e.g. one having the formula RYH), but coordination of the nitrogen atom of the Schiff base ligand to the metal or silicon or other atom having an atomic mass from 27 to 124 of the activating compound occurs less frequently because it competes unfavourably with the protonation / decoordination mechanism resulting from the in situ generation of a strong acid (such as a hydrogen halide). This alternative mechanism is however quite effective in the catalysis of metathesis reactions of organic compounds since it provides a more random distribution of the strong acid formed in the reaction mixture than if the same strong acid is introduced directly in the presence of the multicoordinated metal complex.

Problems solved by technology

Although providing an improvement over existing ROMP catalysts, the teaching of U.S. Pat. No. 6,284,852 is however limited in many aspects, namely: because its alleged mechanism of acid activation involves the protonation of phosphine ligands, it is limited to alkylidene ruthenium complexes including at least one phosphine ligand; it does not disclose reacting a Schiff-base-substituted ruthenium complex with an acid under conditions such that said acid at least partly cleaves a bond between ruthenium and the Schiff base ligand of said complex.

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