| Research Abstract |
Five coordinate ruthenium complexes [RuH(P-P)_2]PF_6 were prepared with various phosphines such as dppe, dppp, dpppb,diop, dppf, binap, where dppe is 1,2-bis(diphenylphosphino)ethane, dppp is 1,3-bis(diphenylphosphino)propane, dppb is 1,4-bis(diphenylphosphino)-propane, diop is 2,3-o-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, dppf is 1,2-bis(diphenylphosphino)ferrocene, binap is 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl. The NMR studies of these complexes indicated that they have a 6th ligand such as solvent, nitrogen molecule and so on, in solution. When complexes have large chelate rings with phosphines, observed were predominant formation of cis isomers with agostic interactions with phenyl group of phosphines. Further investigations with dppb under argon, nitrogen or hydrogen atmosphere revealed that this agostic interaction was stronger than the coordination of nitrogen molecule or solvent, and weaker than molecular hydrogen coordination. The structure of dpp
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f-complex was determined by x-ray study, indicating the cis-structure due to the steric hindrance of dppf. Hydrogen molecule coordinated to this complex to give novel type of molecular hydrogen complex. T_1 value of H_2 ligand of this complex showed that the H_2 and original hydride ligands are equivalent, in other word, this was a trihydride complex.
In the case of zirconium species, we found the followings. The active species quantitatively formed from zirconocenedialkyls were zirconocene(II) olefin complexes. The structure of zirconocenestilbene complex was determined by x-ray analysis. Reactions of zirconocene olefin complexes with another olefins gave olefin-olefin cross coupling products with >99% of regio-selectivities and >99% of stereo-selectivities. In addition the detail investigations of its mechanism led the development: of novel skeleton rearrangement by carbon-carbon bond activation in the case of zircona- or hafnacyclopentane derivatives. Methyl group of alpha-position could be transferred to beta-position selectively by this novel method. Less
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