The method of Van Meurs et al.  for hydrogenation of ferrocene has been extended to include a variety of bridged ferrocenes. Singly bridged and dibridged ferrocenes containing tri-, tetra-, or pentamethylene bridges were hydrogenated to the corresponding polycyclic hydrocarbons. Conditions required were consistent with a mechanism that involves an initial protonation of the iron atom. Bridge opening to a propylferrocene derivative was observed for the compound with three not-all adjacent trimethylene bridges, and no hydrogenation reaction was observed for the corresponding derivative with tetramethylene bridges. Without catalyst or hydrogen, trifluoroacetylation and a rearrangement of a bridge were observed in the tris(trimethylene) compound. In the presence of catalyst but no hydrogen, an alpha alcohol and the corresponding diferrocenyl ether were obtained. Possible mechanisms are suggested for these reactions.
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