A Proposed Reversible Mechanism Confirming Conformational Retention in 1, 12-Dimethyl[l. l]Ferrocenophane

Abstract

Upon examination of the reaction of l, 12-dimethyi[l.l]ferrocenophane with the strong non-oxidizing acid boron trifluoride, a dication was formed. Upon dilution widi H₂O, a bridge carbocation results. A mixture of exo-exo l, 12-dimethyl[l.l]ferro-cenophane and exo-endo l, 12-dimethyl[l.l]ferrocenophane should be observed, if the hydride is added direcdy back to the methylene bridge carbocation. However, when the hydride is added, retention of configuration is realized, indicating a significandy more complex mechanism of reaction. We propose that the iron centers and the methylene bridge participate through an intramolecular hydride migration which leads to retention of configuration.