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.

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.

Photolysts of cis-(Me2SiSiMe2)[η5-t-BuC5H3)Fe(CO)]2(u-CO)2(2c) in the presence of P(Oph)3 ligands afforded only cis-[η5:η5-t-BuC5H3Me2SiSiMe2C5H3-t-Bu)Fe2(CO)P(Oph)3(μ-CO2](3c), whereas similar traeatment of 2t yielded only the trans isomer 3t. When 3c and 3t were heated, in xylene, the cis compound (3c) rearranged to the trans product [{Me2Si(η5-t-BuC5H3)Fe}2(CO)3P(OPh)3](4t), while the trans compound (3t) afforded the cis product [{Me2-Si(η5-t-BuC5H3)Fe}2(CO)3P(OPh)3] (4c); thus, the rearrangement is stereospecific.

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.

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.