Reactions of CpArCHCHArCp [Ar=Ph (1), p-MeOC6H4 (2)] with Ru3(CO)12 in refluxing xylene afforded the unexpected bridgeing C-C cleavage and cyclopentadienyl coupling products: the 2,2'-bisubstituted fulvalene diruthenium complexes (η5:η5-2,2'-ArCH2C5H3C5H3CH2Ar)Ru2(CO)4 [Ar=Ph (5),p-MeOC6H4 (9)] and the partially hydorgented products (η5:η3-ArCH2C5H3C5H6CHAr)Ru2(CO)4 [Ar=Ph(4), p-MeOC6H4 (8)], in addition to the normal bridged bis(cyclopentadienyl) tetracarbonyl diruthenium complexes (ArCHCHAr)[η5-C5H4)Ru(CO)]2(μ-CO)2[Ar=Ph(7),p-MeOC6H4 (10)]. When ligand (tBuC5H4)PhCHCHPh(tBuC5H4) (3) reacted with Ru3(CO)12, the tetrasubstituted fulvalene diruthenium complex (η5:η5-PhCH2tBuC5H2C5H2tBuCH2Ph)Ru2(CO)4 (11) and three normal bridged bis-(cyclopentadienyl) diruthenium complexes (PhCHCHPh)[(η5-tBuC5H3)Ru(CO)]2(μ-CO)2 (12-14) were obtained. The molecular structures of 4, 5, 7-meso, 7-rac, 8, 10-meso, 11, 12, 13, and 14 were determined by X-ray diffraction. The stereochemistry of the reaction was also studied, and the possible mechanism was discussed.

Treatment of (Me2SiSiMe2)[η5-C5H3R1)Fe(CO)]2(u-CO)2(R1=H(1), R1=t-Bu(5)) with R2NC(R2=C6H11, t=Bu) in benzene afforded isocyanide-substituted complexes [(η5:η5-C5H3R1-Me2SiMe2C5H3R1)Fe2(CO)(CNR2)(u-CO)2] (R1=H, R2=t-Bu(4); R1=R2=t-Bu(6)). Turther investigations indicated that the cis substrate 5c afforded only the cis product (6c), while the trans substrate 5t afforded only the trans product (6t). When 3 and 4 were heated respectively in xylene, three different rearranged products (6t). When 3 and 4 were heated respectively in xylene, three different rearranged products [{(Me2Si)(η5-C5H4)-Fe(CO)L1}{(Me2Si)(η5-C5H4)-Fe(CO)L2}](L1=L2=CO(2); L1=C6H11NC, L2=CO(7), L2=C6H11NC(9); L1=t-BuNC, L2=CO(8), L2=t-BuNC(10)) were obtained. Similarly, thermal treatment of 6t afforded three different cls rearranged products, 11c, 12c, and 13c, while treatment of 6c afforded three different cis rearranged products, 11t, 12t, and 13t, This indicated that the rearrangement still follows the reaction mechanism proposed previously on the basis of the intramolecular nature of this reaction mechanism proposed previously on the basis of the intramolecular nature of this reaction if we only take into accunt the configuration of two tert-buty1 groups on the Cp rings. To explain the formation of three different products, an alternative mechanism involving free ligand exchange to from three different iron-centerde radical intermediater is proposed as a supplement to the previous mechanism. The complex stereochemistry in the moecules of 12 and 13 is discussed. Molecular structures of 8,9t, 12t, and 13c 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.

Dimolybdenum complexes (X) (Y) [(η5-C5H3)Mo(CO)3]2 [Y=Me2Si, X=Me2C, (CH2)5C, CH2; Y=Ph2Si, X=Me2C] and desilylation products (X)[(η5-C5H4)Mo(CO3)2 were obtained from the reactions of carbon and sliicon doubly bridged biscyclopentadiene ligands (X) (Y) (C5H4)2 with Mo(CO)6 in refluxing xylene. When these ligands reacted with W(CO)6, under similar conditions, in addition to ditungsten complexes (X) (Y) [(η5-C5H3)W(CO)3]2 [X=Me2C; Y=Me2Si, Ph2Si] and desilylation products (X) [(η5-C5H4)W(CO)3]2, a class of structurally novel comolexes (X) (η5-C5H3) [(Y)W(CO)3][W(CO)3][for X=Me2C, (CH2)5C; Y=Me2-Si] with a W-Si bond were also isolated. The reactions of carbon and germanium dobuly bridged biscyclopentadiene ligands (X)(Me2Ge)(C5H4)2[X=Me2C, (CH2)5C] with Mo(CO)6 or W(CO)6 gave similar novel complexes (X)(η5-C5H3)(η5, η1-C5H3)[(Me2Ge)M(CO)3][M(CO)3][X=Me2C, (CH2)5C; M=Mo, W] with a M-Ge bond. The reactions also produced degermylation products. However, the corresponding dimolybdenum or ditungstem complexes were not isolated in these cases. The molecular structures of 2, 6, 8, 10, 11, 13, 14, 15, 19, 21, 22, 25t, and 26t have benn determinde by X-ray diffraction. The M-M distances in complexes 2 [3.4328(12)A], 8 [3.453(2)A], and 11 [3.403(2) A] are conspicuously elongated and are in fact the longest ever reported among the biscyclopentadienyl dimolybdenum or ditungsten complexes. The factors affecting the structures of dimolybdenum or ditungsten complexes are discussed.

When the doubly bridged bis(cyclopentadiene) ligand (Me2C)(Me2Si)(C5H4)2 (1) reacted with Fe(CO)5 in refluxing toluene, the unusual product [(C5H6)(Me2C)(Me2Si)(η5-C5H3)Fe(CO)]2-(μ-CO)2 (2) with a hydrogenated double bond in one of the cyclopentadiene ligands, the diiron complex (Me2C)(Me2Si)[(η5-C5H3)Fe(CO)2]2 (3), and the desilylation product 4 were obtained. When the reaction was performed in refluxing xylene, the novel complex (Me2C)(η5-C5H3)-(η5:η1-C5H3)[(Me2Si)Fe(CO)2][Fe(CO)2] (5) with and Fe-Si bond, which should be accompanied by the cleavage of a C-Si bond in the ligand, was isolated in addition to the complees 2～4. When bis(cyclopentadienyl) ligands bridged with R2C (R2C=Me2C, (CH2)5C)AND Me2E(E=Si, Ge) groups were used instead of 1, the similar novel complexes (R2C)(η5-C5H3)(η5:η1-C5H3)[(Me2E)Fe(CO)2] (R2C=Me2C, E=Ge (7); R2C=(CH2)5C, E=Si(17), Ge (21)) with and Fe-E bond were obtained in addition to the diiron complexes (R2C)(Me2E)-[(η5-C5H3)Fe(CO)]2[Fe(CO)2](R2C=Me2C, E=Ge (8); R2C=(CH2)5C,E=Si (18), Ge (22)) and the desilylation or degermylation products. When a tert-butyl group was introduced into the cyclopentadienyl rings, or two phenyl groups were introduced at the bridging silicon atom instead of two methyl groups in 1, only the diiron complexes (Me2C)(Me2E)[η5-t-BuC5H2]Fe(CO)2]2 (E=Si(10), Ge (13)) and (Me2C)(Ph2Si)[(η5-C5H3)Fe(CO)2]2 (15) were obtained, in addition to the desilylatin or degermylation products. Whem a methylene bridge was used instead of an isopropylene bridge in 1 and 6, the partially hydrogenated complexes (Me2E)(η3-CHC5H6)(η5-C5H3)Fe(CO)3Fe(CO)2(E=Si(24),Ge (28)), the diiron complexes (CH2)(Me2E)[(η5-C5H3)Fe(CO)]2(μ-CO)2(E=Si (25), Ge (29)), and the desilylation or degermylation products were obtained. The molecular structures of 2, 3, 5, 7, 8, 10, 11t, 15, 17, 18, 21, 24, 25, 28, and 29 were determinde by X-ray diffraction.