(1) The cationic species derived from (C_5M_<e5>) RuCl (diene) and silver ion was founde to be highly selective catalysts for [4+4] cyclodimerization of butadiene or isoprene. The structure of an intermediate 1,3,7-octatriene complex was determined unequivocally by single crystal X-ray analysis. In the case of 1,3-pentadiene, regioselective linear dimerization of the diene took place by way of a bis (pi-allylic) ruthenium (IV) intermediate which structure was determined. by X-ray analysis. Formation of eight-membered caarbocyles is explained in terms of a metallacycle mechanism invovling rethenium induced C-C bond formation of the coordinated 1,3,7-octatriene ligand.
(2) A dichloro (ethelene) ruthenium (II) complex involving designed terdentate chiral auxiliary, 2,5-bis [4'- (S)-isoproploxazolin-2'-yl] pyrdine (ip-pybox) was found to be highly stereo-and enantio-selective catalyst for asymmetric cyclopropanation of terminal alkenes with seberal alkyl diazoacetates. Ethylene, carbon mono
xide, and carbene complexes involving the RuC12(pybox) fragment were prepared, and the structures and thier chemical behavior was studied in order to elucidate reasonable mechanism. Ruthenium (II) carbenoid species derived from (C_5M_<e5>) Ru fragments were found to be efficient catalyst for metathesis polymerization of norbornene.
(3) The complex, Ru (COD) (COT), COT=1,3,5-cyclooctatriene ; COD=1,5-cyclooctadiene, induced new double cycloaddition towards two melecules of alkyl propiolates. One alkyne added to the COT ligand in a [6+2] cycloaddition mode, whereas the other to the COD ligand in a [2+2+2] one, to result in the final formation of bicyclo [4.2.2] decadiene framework.
(4) Hydrogenation of acenephtylene or aceanthrylene ligands facially coordinarted to the trinuclear rethenium carbonyl cluster followed by treatment with carbon monoxide furnished new 4,5-dihydro derivatives with a fulven partial structure.
(5) New C_<60> complexes of transition metal fragments were prepared in order to develop new ligand fields for selective C-C bond formation. Less