A novel trigonal-bipyramidal ruthenium car-bonyl cluster, [(μ3-Ge){Ru(CO)2(η5-C5Me4H)}]2Ru3(CO)9(3), was accidentally synthesized by thermal treatment of Ru3(CO)12 and C5Me4HMe2GeGeMe2C5Me4H in boil-ing decalin, along with the dinuclear ruthenium complex [(Me2Ge)(η5-C5Me4)Ru2(CO6] (4). Similar treatment of Ru3(CO)12 and C5H5Me2GeGeMe2C5H5 in boiling hep-tane afforded three different bimetallic complexes, [(Me2-Ge)(η5-C5H4)Ru2(CO)6] (1), [(Me2Ge)(η5-C5H4)Ru(CO)2]2 (2), and dimer [(η5-C5H5)Ru(CO)2]2. Molecular structures of 2,3, and 4 have benn determined by single-crystal X-ray diffraction.

The ansa-metallocene complexes Me2Si(η5-C5H4)(η5-C5Me4)MEI2[M=Ti(1),Zr(2),Hf(3)] were prepared by the reaction of [Me2Si(η5-C5H4)(η5-C5Me4)]Li2 with MCI4 2THF. Complexes Me2Ge(η5-C5H4)(η5-C5Me4)MCI2[M=Ti(4),Zr (5)]were synthe-sized using similar method from the germyl-bridged ligand. The molecular structures of 1-3 and 5 have been determinde by X-ray diffraction. Complexes 1-3 and 5 in combination with MAO were studied as catalysts for ethylene polymerization and it was found that zirconocene catalysts show much higher activities than the titanocene and hafnocene and the activities reach the maximum at high temperature. This indicates that the zirconocene system based upon [Me2E(C5H5)(C5Me4)]2 (E=Si, Ge) supporting coordination is a highly stable ethylene polymerization catalyst system. The relationship between structures and catalytic properties of catalysts is discussed.

The ansa-metallocene complexes Me2Ge(η5-C5Me4)2MCI2[M=Ti(1), Zr(2)], Me2Ge(η5-C5H3Bu-t)2ZrCl2(3) and Me2Ge(η5-C5H4)(η5-C5H3R)ZrCl2[R=Me(4), t-Bu (5)] were prepared by the reaction of the corresponding ligands with n-BuLi and MCl4 2THF, respectively. The molecular structures of 1 and 2 have benn determinde by the X-ray diffraction method. Complexe 2-5 in combination with MAO were studied as catalysts for ethylene polymerizatiion and all the germyl-bridged zirconocene catalysts show high activities at relative high temperatures. This indicates that the germyl-bridged zirconocene systems show thermally stable catalyst sysstems for polymerization of ethylene.

A series of doubly bridged dinuclear titanium and zirconium complexes (Me2C)(Me2E)(C5H3)2(Cp'MCI2)2 [E=Si,Cp'=C5H5, M=Ti (1), Zr (2); E=Ge, Cp'=C5H5, M=Ti (3), Zr (4); Cp'=C5Me4H, M=Zr, E=Si (5), Ge (6)] and (Me2SiOSiMe2)2(C5H3)2(Cp'MCI2)2[Cp'=C5H5, M=Ti (7), Zr (8); Cp=C5Me4H, M=Zr (9)] were synthesized by the reaction of the lithium compounds of the corresponding doubly bridged cyclopentadienyl ligands with CpTiCl3, CpZrCl3(THF)2 or C5Me4HZrCl3, respectively. These complexes were characterized by 1H-NMR, MS and elemental analysis. The crystal structure of 4 was determined by the X-ray diffraction. Their catalytic properties for ethylene polymerization were also studied in the presence of MAO.

A series of doubly bridged bis(cyclopentadienyl) tetracarbonyl diiron complexes (7-13) have been synthesized by the reaction of the corresponding ligand (1-6) with Fe(CO)5 in refluxing xylene. It is unusual that the reaction of ligand (GeMe2)(GeMe2)(C5H4)2 (3) with Fe(CO)5 gave the complex (GeMe2)[η5-C5H4)Fe(CO)]2(μ-CO)2 (10) as the main product which lost the GeMe2, only a small amount of the expected product (GeMe2)2[(η5-C5H3)Fe(CO)]2(μ-CO)2 (9) was obtained. The molecular structures of 9 and (SiMe2SiMe2)2[(η5-C5H3)Fe(CO)]2(μ-CO)2 (13) have been determined by X-ray diffraction.