Theory-assisted design of catalysts for olefin metathesis. Investigation of novel third-row transition metal complexes (se prosjekt 160072)

The long-term goal of the project is to develop new catalysts for olefin metathesis that allows for better stereocontrol of the product alkenes. Massive screening involving density functional theory (DFT) and multivariate data analysis (QSPR/QSAR) is perf ormed to aid the experimental efforts and to reduce the number of compounds subjected to synthesis. The project proceeds as a collaboration between three research groups with expertise in catalysis, organic and organometallic chemistry, multivariate model ing (QSPR/QSAR), and computational transition metal chemistry. We focus on the ring-closing metathesis (RCM) reaction for which the lack of rational control of the formation of cis and trans olefinic products poses limitations on the application of metath esis in organic synthesis. Contemporary ruthenium alkylidene catalysts are highly active and robust, but their inherent symmetry hampers the development of Ru-based catalysts with excellent stereocontrol. The current project devotes itself to a systematic search for novel transition metal complexes with electronic properties comparable to those of the Ru-based catalysts, but with lower symmetries and better opportunities for control of the stereoselectivity through substitution. The screening involves var iation of both metal and ligand and the potential catalysts, the metal—alkylidene complexes, are generated in a combinatorial fashion. Multivariate methods are used to select subsets of representative ligands from a library of more than 250 transition met al ligands for use in the combinatorial generation of complexes. The number of complexes still grows rapidly as a function of the number of ligands and metals involved, and accordingly the currently proposed investigation is limited to groups 5—10 (Ta—Pt) of the third-row transition metals.