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.

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.

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.

Thermal treatment of 1,2-bis(3-tert-butylcyclopentadieny1) tetramethyldigermane with [Fe(CO)5] in xylene gave the diiron complex [Fe2(CO)2(μ-CO)2(μ-3-t-BuC5H3Me2GeGeMe2C5H3Bu-t-3)] 1 existing as a mixture of cis and trans isomers (1c and 1t) which were separated by preparative TLC. When the two isomers were heated in xylene the cis substrate (1c) rearranged to a trans product [Fe2(CO)4(μ-3-t-BuC5H3GeMe2)2] 2t, while the trans substrate (1t) afforded a cis product 2c. This indicated that the rearrangement reaction is stereospecific, which is consistent with previous results. Molecular structures of 1c, 1t, 2t, and 2c were determinde by X-ray diffraction.