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 ca ...

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 derivatives.

Preparation and structure

Cyclopentadienylthallium is prepared by the reaction of thallium(I) sulfate, sodium hydroxide, and cyclopentadiene: : 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 a ...

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, 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