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.

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.

Complexes (Me2GeGeMe2)[η5-C5R4)Fe(CO)]2(u-CO)2(R=H, 1; Me, 3) 1 and 3, prepared by the reaction of C5R4HMe2GeGeMe2C5R4H with Fe(CO)5 in refluxing xylene, underwent a novel thermal reaction between their Ge-Ge and Fe-Fe bonds, forming corresponding rearrangement products with new cyclic structures, [Me2Ge(η5-C5R4)Fe(CO)2]2(R=H, 2; Me 4). Compared with the case of silicon, the weaker Ge-Ge bond resulted in an easier rearrangement reaction. Reactions of 1 with indine and sodium amalgam were examined. Molecular structures of 1, 2, 3, and 4 were determined by X-ray diffraction.

The binuclear ruthenium complex (Me2-SiSiMe2)[(η5-C5H4)Ru(CO)]2(μ-CO)2(3) was obtained in poor yield by reaction of Ru3(CO)12 with C5H5Me2-SiSiMe2C5H5 in boiling heptane. A thermal rearrange-ment reaction of 3 in heptane afforded the complex [(Me2Si)(η5-C5H4)Ru(CO)2]2 (4), which was evidently formed via a metathesis between Si-Si and Ru-Ru bonds in 3. Molecular structures of 3 and 4 have been determined by X-ray diffraction.

The catalytic hydrogenation of the indenyl complex(Me2SiSiMe2)[η5-Ind)Fe(CO)]2(μ-CO)2(2) in CH2Cl2 afforded the tetrahyroindenyl complex (Me2SiSiMe2)[(η5-IndH4)Fe(CO)]2(μ-CO)2 (3), existing as a mixture of cis and trans isomers (3c and 3t), which were separated by column chromatography. When the two isomers were heated in xylene, respectively, the cis substrate 3c rearranged to the trans product [Me2Si(η5-IndH4)Fe(CO)2]2 (4c). This indicates that the rearrangement reaction is stereospecific, which is consistent with the result observed in the rearrangement of complex(Me2SiSiMe2)[η5-t-BuC5H3)Fe(CO)]2(μ-CO)2(5). By analogy with the mechanism porposed based on detailed investigation of 5, the pathway for formation of 4 is described. Molecular structures of 3c, 3t, 4t, and 4c were determinde by X-ray diffraction.