Bridged ferrocenes—VI Synthesis and stereochemistry of [1,1]ferrocenophanes

Synthetic routes to compounds of the [1.1]ferrocenophane class have been devised making use of fulvene and acid chloride precursors and the parent compound has been prepared by direct synthesis. The bridged ferrocenes obtained by these different approaches have been chemically interrelated and their structure and stereochemistry have been investigated through study of their spectral properties. Sodamide promotes intramolecular cyclisation of 1,1′-bis(-cyclopentadienylideneethyl)ferrocene to a [3]ferrocenophane derivative.