Metallocenium ions The most famous example is ferrocenium, , the blue iron(III) complex derived from oxidation of orange iron(II) ferrocene. The lithocene anion, [Li(C5H5)2]–, is the best-documented example of a metallocene anion; otherwise such ions are little known.
Metallocenium ions The most famous example is ferrocenium,  the blue iron(III) complex derived from oxidation of orange iron(II) ferrocene. The lithocene anion [Li(C5H5)2]–, is the best-documented example of a metallocene anion; otherwise such ions are little known.