Lithium cyclopentadienide is an organolithium compound with the formula C<sub>5</sub>H<sub>5</sub>Li. The compound is often abbreviated as LiCp, where Cp<sup>−</sup> is the cyclopentadienide anion. Lithium cyclopentadienide is a colorless solid, although samples often are pink owing to traces of oxidized impurities.
Lithium cyclopentadienide is commercially available as a solution in tetrahydrofuran. It is prepared by treating cyclopentadiene with butyllithium:
Because lithium cyclopentadienide is usually handled as a solution, the solvent-free solid is rarely encountered. According to X-ray crystallography, LiCp is a "polydecker" sandwich complex, consisting of an infinite chain of alternating Li<sup>+</sup> centers sandwiched between ü-÷<sup>5</sup>:÷<sup>5</sup>-C<sub>5</sub>H<sub>5</sub> ligands. In the presence of amines or ethers, LiCp gives adducts, e.g. (÷<sup>5</sup>-Cp)Li(TMEDA). LiCp is a common reagent for the preparation of cyclopentadienyl complexes.