SYNTHESIS, CHARACTERIZATION, AND MOLECULAR-STRUCTURE OF (ETA-5-CYCLOPENTADIENYL)(ETA-4-2,4-CYCLOPENTADIEN-1-ONE)RUTHENIUM(II) COMPLEXES

The complexes [Ru(II)Cp(CPD)(CH3CN)]+ (1) and [Ru(II)Cp(CPD)]22+ (2) (CPD = 2,4-cyclopentadien-1-one) have been shown to be convenient precursors to derivatives resulting from attack by certain nucleophiles at the rings. With nitriles, pyridine, 4,4'-bipyridine, halides, thiourea, N,N-dimethylthioformamide, isocyanides, thioethers, and triphenylarsine, substitution at the rings is not observed, but rather conversion to mononuclear products of the type [Ru(II)Cp(CPD)(nucleophile)].0,+ The reactions are remarkably clean, and complexes derived from the alternative mode of attack comprise less than 5% of the product mixture. Details of the preparative procedures, of characterization of the products by NMR and IR spectroscopy, and of the structure determination of the PF6- salts of 1 and 2 by X-ray diffraction are reported. 1 crystallizes in the monoclinic space group P2/1n with a = 11.833(3) angstrom, b = 11.314(2) angstrom, c = 12.108(3) angstrom and beta = 118.56(2)-degrees; V = 1435.5(6) angstrom3 with rho(cal) = 2.00 for Z = 4. Species 1 is monomeric, with each Ru ligated to Cp (eta5 mode), CPD(eta4), and acetonitrile. 2 crystallizes in the monoclinic space group P2 with a = 8.569(1) angstrom, b = 6.667(1) angstrom, c = 10.561(2) angstrom, and beta = 100.08(2)-degrees; V = 594.0(2) angstrom3 With rho(cal) = 2.19 for Z = 2. The structure consists of dimeric species. Each Ru(II) coordination sphere contains an eta5 Cp ring, an eta4 CPD ring, and an oxygen atom from a second CPL ligand. In both structures, the CPD ring is nonplanar.