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.

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.

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.