Synthesis and reactivity of ruthenium amine and amido complexes

by 1975- Conner, David Michael

CONNER, DAVID MICHAEL. Synthesis and Reactivity of Ruthenium Amine and Amido Complexes. (Under the Direction of Dr. T. Brent Gunnoe) Late transition metal complexes with non-dative and ?-donating ligands are important substrates in a variety of synthetic transformations including C-N or C-O bond forming processes and C-H bond activation reactions. Examples of such complexes are few relative to early and middle transition elements in high oxidation states, and the understanding of the chemistry of such systems with amido, oxide, imido, or oxo ligands has lagged compared to related M-C or M-H linkages. A series of Ru(II) amido complexes of the type TpRu(L)(L')NHR (L = L' = PMe3 or P(OMe)3 or L = CO and L' = PPh3; R = H, Ph, or tBu) were prepared and characterized. These complexes exhibit basic reactivity and will deprotonate C-H bonds as evidenced by the reactivity with weak acids such as 1,4-cyclohexadiene or phenylacetylene. The nucleophilicity of the complexes was also examined by reaction with ethylbromide. In addition, oxidation of the phenyl amido complexes with AgOTf, Cp2FePF6, or I2 resulted in 4,4' carbon-carbon coupling of the aryl group of the anilido ligands to produce the bimetallic complexes [TpRu(L)(L')NHC6H4-]2[X]2 (X = OTf -, PF6-, or I-). The five-coordinate amido complexes (PCP)Ru(CO)NHR (PCP = C6H3(CH2PtBu2)2; R = H or Ph) were synthesized and characterized. The parent amido complex was prepared by deprotonation of (PCP)Ru(CO)(NH3)Cl and the phenyl amido complex was prepared by reacting (PCP)Ru(CO)OTf with LiNHPh. The reactivity of the parent amido complex with phenylacetylene, dihydrogen, and hydrocarbons was studied. Density functional theory was applied to the activation of H2 and CH4 by (PCP')Ru(CO)NH2 (PCP' = C6H3(CH2PH2)2) to yield (PCP')Ru(CO)(NH3)X (X = H or Me). Additionally, the complex (PCP)Ru(CO)Me was prepared. The complexes (PCP)Ru(CO)X (X = Me, NH2, and NHPh) undergo intramolecular C-H bond activation reactions with a tBu arm of the PCP ligand to produce the cyclometalated complex (PCP*)Ru(CO) (PCP* = C6H3(CH2PtBu2){P(tBu)(C(CH3)2CH2)} and methane, ammonia, or aniline, respectively.