Cyclopentadienylthallium

Cyclopentadienylthallium

Names
IUPAC name Thallium(I) cyclopentadienide
Other names Thallium cyclopentadienide (η5-Cyclopentadienyl)thallium
Identifiers
CAS Number	34822-90-7
3D model (JSmol)	Interactive image
ChemSpider	24721800 Y
ECHA InfoCard	100.047.466
EC Number	252-229-2
PubChem CID	97304
InChI InChI=1S/C5H5.Tl/c1-2-4-5-3-1;/h1-5H;/q-1;+1 Key: CVEQRUADOXXBRI-UHFFFAOYSA-N InChI=1/C5H5.Tl/c1-2-4-5-3-1;/h1-5H;/q-1;+1 Key: CVEQRUADOXXBRI-UHFFFAOYAE
SMILES [cH-]1cccc1.[Tl+]
Properties
Chemical formula	C5H5Tl
Molar mass	269.48 g·mol−1
Appearance	Light yellow solid
Melting point	300 °C (572 °F; 573 K)
Solubility in water	Insoluble
Hazards
GHS labelling:
Pictograms
Signal word	Danger
NFPA 704 (fire diamond)	3 0 0
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.

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 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 (Cp) transfer reagents, such as cyclopentadienyl sodium, CpMgBr and Cp₂Mg, cyclopentadienylthallium is less air sensitive. It is also much less of a reducing agent.