From Wikipedia, the free encyclopedia
Jump to: navigation, search
IUPAC name
Thallium(I) cyclopentadienide
Other names
Thallium cyclopentadienide
3D model (JSmol)
ECHA InfoCard 100.047.466
Molar mass 269.48 g·mol−1
Appearance Light yellow solid
Melting point 300 °C (572 °F; 573 K)
Very Toxic T+
R-phrases (outdated) R26/28, R33, R36/37/38
S-phrases (outdated) S13, S28, S45
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.[1]

Preparation and structure[edit]

Cyclopentadienylthallium is prepared by the reaction of thallium(I) sulfate, sodium hydroxide, and cyclopentadiene:[2]

Tl2SO4 + 2 NaOH → 2 TlOH + Na2SO4
TlOH + C5H6 → TlC5H5 + H2O

The compound adopts a polymeric structure, consisting of infinite chains of bent metallocenes. The Tl---Tl---Tl angles are 130°.[3] Upon sublimation, the polymer cracks into monomers of C5v symmetry.


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.


  1. ^ C. Elschenbroich, (2006). Organometallics. Wiley-VCH, Weinheim. p. 130. ISBN 3-527-29390-6. 
  2. ^ A.J. Nielson; C.E.F. Rickard; J.M. Smith (1986). "Cyclopentadienylthallium (Thallium Cyclopentadienide)". Inorg. Synth. 24: 97–99. doi:10.1002/9780470132555.ch31. 
  3. ^ Falk Olbrich, Ulrich Behrens "Crystal structure of catena-cyclopentadienylthallium, [Tl(C5H5)]" Zeitschrift für Kristallographie - New Crystal Structures 1997, 212, 47-47.