Rigid bent bridges between cyclopentadienylmetal fragments. Iorn derivatives of the 4,8-ethano-2,4,6,8-tetrahydro-s-indacene-2,6-diyl dianion

From the reaction of the 4,8-ethano-2,4,6,8-tetrahydro-s-indacene-2,6-diyl dianion (L) and cyclopentadienyl (Cp) anion with iron(II) chloride the bridged ferrocenes syn,syn-CpFeLFeCp (4), syn,anti-CpFeLFeCp (5), and all-syn-CpFeLFeLFeCp (6) were obtained. The structures of 4-6, including syn, anti isomerism, were deduced from their 1 H and 13 C NMR and mass spectra. X-ray crystal analyses were carried out for 4 and 5