Cyclopentadienylthallium, also known as thallium cyclopentadienide, is an organothallium compound with formula C₅H₅Tl. This light yellow solid is insoluble in most organic solvents, but sublimes readily. It is used as a precursor to

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that c ...

and main group

cyclopentadienyl complex A cyclopentadienyl complex is a coordination complex of a metal and cyclopentadienyl groups (, abbreviated as Cp−). Cyclopentadienyl ligands almost invariably bind to metals as a pentahapto (''η''5-) bonding mode. The metal–cyclopentadien ...

es, as well as organic

cyclopentadiene Cyclopentadiene is an organic compound with the formula C5H6.LeRoy H. Scharpen and Victor W. Laurie (1965): "Structure of cyclopentadiene". ''The Journal of Chemical Physics'', volume 43, issue 8, pages 2765-2766. It is often abbreviated CpH beca ...

derivatives.

Preparation and structure

Cyclopentadienylthallium is prepared by the reaction of

thallium(I) sulfate Thallium(I) sulfate (Tl2SO4) or thallous sulfate is the sulfate salt of thallium in the common +1 oxidation state, as indicated by the Roman numeral I. It is often referred to as simply thallium sulfate. Uses During the last two centuries, Tl2SO4 ...

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkal ...

, and

: : Tl₂SO₄ + 2 NaOH → 2 TlOH + Na₂SO₄ : TlOH + C₅H₆ → TlC₅H₅ + H₂O The compound adopts a

polymer A polymer (; Greek ''poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and ...

ic structure, consisting of infinite chains of bent metallocenes. The Tl---Tl---Tl angles are 130°.Falk Olbrich, Ulrich Behrens "Crystal structure of catena-cyclopentadienylthallium, l(C₅H₅) Zeitschrift für Kristallographie - New Crystal Structures 1997, 212, 47-47. Upon sublimation, the polymer cracks into monomers of C_5v symmetry.

Applications

Compared to other cyclopentadienyl (Cp) transfer reagents, such as

cyclopentadienyl sodium Sodium cyclopentadienide is an organosodium compound with the formula C5H5Na. The compound is often abbreviated as NaCp, where Cp− is the cyclopentadienide anion. Sodium cyclopentadienide is a colorless solid, although samples often are pin ...

, CpMgBr and Cp₂Mg, cyclopentadienylthallium is less air sensitive. It is also much less of a reducing agent.

References

{{Cyclopentadiene complexes Cyclopentadienyl complexes Organothallium compounds Half sandwich compounds Thallium(I) compounds