Cyclopentadienylthallium

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 and main group cyclopentadienyl complexes, as well as organic cyclopentadiene derivatives.

Preparation and structure

Cyclopentadienylthallium is prepared by the reaction of thallium(I) sulfate, sodium hydroxide, and cyclopentadiene:
The compound adopts a polymeric structure, consisting of infinite chains of bent metallocenes. The Tl---Tl---Tl angles are 130°. Upon sublimation, the polymer cracks into monomers of C_5v symmetry.

Applications

Compared to other cyclopentadienyl transfer reagents, such as cyclopentadienyl sodium, CpMgBr and Cp₂Mg, cyclopentadienylthallium is less air sensitive. It is also much less of a reducing agent.