[1] Sodium cyclopentadienide is a colorless solid, although samples often are pink owing to traces of oxidized impurities.

Sodium cyclopentadienide is a common reagent for the preparation of metallocenes.

[9] The nature of NaCp depends strongly on its medium and for the purposes of planning syntheses; the reagent is often represented as a salt Na+C5H−5.

Crystalline solvent-free NaCp, which is rarely encountered, is a "polydecker" sandwich complex, consisting of an infinite chain of alternating Na+ centers sandwiched between μ-η5:η5-C5H5 ligands.

[10] As a solution in donor solvents, NaCp is highly solvated, especially at the alkali metal as suggested by the isolability of the adduct Na(tmeda)Cp.