Synthesis, structures and thermal rearrangement reaction of (Me2SiGeMe2)[(η5-C5R4)Fe(CO)]2(μ-CO)2 (R = H, Me)

Two new bidentate ligands, C5H5Me2SiGeMe2C5H5 (9) and C5HMe4Me2SiGeMe2C5HMe4 (10) were prepared by the reaction of ClMe2SiGeMe2Cl with cyclopentadienyl lithium and tetramethylcyclopentadienyl lithium, respectively. Ligands 9 and 10 reacted with Fe(CO)(5) to yield the diiron complexes (Me2SiCeMe2)-[(eta (5) - C5R4)Fe(CO)](2)(mu - CO)(2) (R = H, 11; R = Me, 13). Complexes 11 and 13 could form the products [(eta (5) - C5R4) Fe(CO)(2)](2) (mu - Me2Si) (mu - Me2Ge) (R = H, 12; R = Me, 14) by a novel intramolecular thermal rearrangement reaction. The crystal and molecular structures of complexes 11, 12, 13 and 14 were determined by X-ray diffraction. The steric effect of the bridged tetramethylcyclopentadienyl ligand on some structural data and the rearrangement reactivity was discussed.