In contrast to benzene, ferrocene cannot be nitrated or halo- genated directly and cannot be sulfonated in concentrated sulfuric acid. Halogens, nitric acid, and sulfuric acid oxidize ferrocene to the ferricinium cation (3)* a stable species which does not undergo electrophilic substitution.

Why cant ferrocene be nitrated?

Ferrocene cannot be directly nitrated or halo- genated because the reagents themselves cause oxidation of ferrocene to the ferricinium ion (4, 5, 6). ... No other direct com- parison of the reactivity of ferrocene with the reactivities of other aro- matic substrates has been reported.

What do you understand by nitration?

: the process of adding a nitro group to an organic compound.