Octahedral ruthenium(II) complexes for C-H bond activation and olefin hydroarylation

Abstract

The study of inert C-H bond activation of hydrocarbons has been gaining interest. As these hydrocarbons are used in the production of many consumables such as fuel, plastics, and detergents, it is necessary to efficiently utilize the finite quantity of petroleum feedstocks. Transition metal complexes are incorporated as catalysts into synthetic routes to create new C-X (X = C, N, O) bonds in order to increase the chemical value of organic molecules. The complex [Ru(η6-p-cymene){P(OCH2CF3)3}(Ph)(OTf)] (1) (P{OCH2CF3}3 = tris(2,2,2-trifluoroethyl) phosphite, Ph = phenyl, OTf = trifluoromethanesulfonate) was prepared and tested for functionality as a catalyst in olefin hydroarylation. Catalytic reactions were attempted with 5 mol % of 1 in ethylene (15 psi) and benzene-d6 at a varying temperatures, which resulted in the decomposition of 1 and no formation of an organic product. With the observed decomposition of the complex in catalytic attempts, three different directions were pursued: the coordination of ligands 1,4,7-trimethyl-1,4,7-triazacyclononane (9N3Me) and 1,4,7-trithiacyclononane (9S3) to complex 1 to replace η6-p-cymene as the ancillary ligand, the synthesis of a Ru(η6-p-cymene) complex that had the caged phosphite ligand trimethylolpropane phosphite {P(OCH2)3CEt} coordinated, and the synthesis of Ru complexes containing the anionic ancillary ligand pentamethylcyclopentadiene (Cp*). The ligands 9S3 and 9N3Me did not coordinate to complex 1. The new complex [Ru(η6-p-cymene){P(OCH2)3CEt}{Ph)(Cl)] (2) was synthesized. The new complex [Ru(Cp*){P(OCH2CF3)3}2(Cl) 3 was synthesized, characterized, and reactivity with AgOTf, AgOAc, PhMgBr, PhLi, and MeLi have been tested (AgOAc = silver acetate)

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