Lithium cyclopentadienide

Lithium cyclopentadienide
Names

Other names lithium cyclopentadienylide, cyclopentadienyllithium, LiCp
Identifiers
CAS Number	16733-97-4^Y
ECHA InfoCard	100.156.001
PubChem CID	14063469
CompTox Dashboard (EPA)	DTXSID40555241
Properties
Chemical formula	C₅H₅Li
Molar mass	72.04 g·mol⁻¹
Appearance	colorless solid
Density	1.064 g/cm³
Solubility in water	decomposition
Solubility	THF, dimethoxyethane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is ^YN ?) Infobox references

Chemical compound

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.

Preparation, structure and reactions

Lithium cyclopentadienide is commercially available as a solution in tetrahydrofuran. It is prepared by treating cyclopentadiene with butyllithium:^[1]

C₅H₆ + LiC₄H₉ → LiC₅H₅ + C₄H₁₀

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.

References

^ ^a ^b Reent Michel; Regine Herbst-Irmer; Dietmar Stalke (2011). "Revealing Coordination Patterns in C₅-Cyclic Lithium Organics". Organometallics. 30 (16): 4379–4386. doi:10.1021/om200471e.
^ Robert E. Dinnebier; Ulrich Behrens & Falk Olbrich (1997). "Solid State Structures of Cyclopentadienyllithium, -sodium, and -potassium. Determination by High-Resolution Powder Diffraction". Organometallics. 16 (17): 3855–3858. doi:10.1021/om9700122.