We have previously shown that the phosphite coordinated diiodo(η6-p-cymene)ruthenium(II) complex, η6-p-cymene)RuI2{P(OCH2)3CEt}, reacts cleanly with phenylmagnesium bromide at room temperature in methylene chloride to yield the phenylated ruthenium(II) complex, (η6-cymene)RuI(Ph){P(OCH2)3CEt}. In light of this facile reactivity, we became interested in the reactivity of diiodo(η6-p-cymene)ruthenium(II) with weaker nucleophiles. Reaction of bis(pyrazol-1-yl)acetic acid ((pz)2HCCO2H, pz = pyrazolyl; BPA) or bis(3,5-dimethylpyrazol-1-yl)acetic acid ((3,5-Me-pz)2HCCO2H, pz = 3,5-dimethylpyrazolyl; 3,5-MeBPA) with diiodo(η6-p-cymene)ruthenium(II) in the presence of potassium carbonate at room temperature in acetonitrile (NCMe) affords octahedral, (η6-p-cymene)(κ3-N,N,O-BPA)Ru(II) (1) and (η6-p-cymene)(κ3-N,N,O-3,5-Me-BPA)Ru(II) (2), respectively. Increasing the reaction temperature to 80° C displaces the cymene ligand of 1 and 2 and yields cationic, tris-acetonitrile ruthenium heteroscorpionate complexes, [(κ3-N,N,O-BPA)Ru(II)(NCMe)3]I (3) and [(κ3-N,N,O-3,5-MeBPA)Ru(II)(NCMe)3]I (4). Compound 2 is sterically congested and displays broad and ill-defined 1H NMR signals, suggesting a fluxional process most likely associated with the liberation of one of the 3,5-dimethylpyrazolyl arms of the 3,5-MeBPA ligand from the metal. All compounds have been characterized by 1H, 13C NMR, infrared spectroscopy and elemental analysis. Compounds 1 and 4 have also been characterized by single crystal X-ray crystallography. Notably, compounds 3 and 4 may serve as synthons for the preparation of a number of new compounds including those capable of performing olefin hydroarylation reactions.

Reactivity of bi(pyrazol-1-yl)acetic acid ligands with diiodo(η6-p-cymene)ruthenium(II)

251st National Meeting (2016)

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