The Grotjahn lab has developed two catalysts that contain a cyclopentadienyl (Cp) ligand as well as a phosphine ligand. These catalysts are highly selective in the production of (E)-alkenes from terminal alkenes. We hypothesize that the high (E)-selectivity originates from the bifunctionality of the phosphine ligand. A potential approach to inducing (Z)-selectivity is to modify the Cp ligand by incorporating bulkier R groups and including a pendant base. Methodologically, we are conducting water and air free synthetic experiments to produce altered Cp ligands. These ligands are characterized by nuclear magnetic resonance and recrystallization, purified by silica gel column chromatography, and subsequently attached to ruthenium metal centers by oxidative addition in water and air free synthetic experiments. The consequent ruthenium complexes are tested for (Z)-alkene isomerization efficacy through iterative nuclear magnetic resonance experiments. Currently, the results of our experiments have yielded a small variety of Cp ligands with one ligand being novel. In addition, a novel ruthenium complex has been synthesized, but has not been tested for any (Z)-alkene isomerization potency, as it is not pure and thus not ready for that step in our protocol. In summary, the synthesis and characterization of functionalized cyclopentadienyl ligands and a respective ruthenium complex will be presented.

Toward (Z)-alkene isomerization

2019 Fall National Meeting

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