Lithium cyclopentadienide is an organolithium compound with the formula C5H5Li. The compound is often abbreviated as LiCp, where Cp− 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:[1]
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+ centers sandwiched between μ-η5:η5-C5H5 ligands.[2] In the presence of amines or ethers, LiCp gives adducts, e.g. (η5-Cp)Li(TMEDA).[1] LiCp is a common reagent for the preparation of cyclopentadienyl complexes.