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Thallium: Organometallic Chemistry

  1. Robert D. Pike

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0225

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Pike, R. D. 2011. Thallium: Organometallic Chemistry . Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. The College of William and Mary, Williamsburg, VA, USA

Publication History

  1. Published Online: 15 DEC 2011


The organometallic chemistry of thallium(I) is dominated by cyclopentadienyl complexes. These may be polymeric through bridging Cp arrangements or oligomeric as a result of Tl⋯Tl contacts. Th[BOND]Cp complexes are easily prepared and are highly useful Cp-transfer agents. There are two known Tl(I) organometallics with direct Tl[BOND]C σ-bonds; one is monomeric and the other is tetrameric due to Tl⋯Tl contact. A variety of Tl(I) π-complexes are recognized. Bonding in the latter tends to be fairly weak.

Two R2Tl[BOND]TlR2 dimers (R = silyl group) are known, but no such Tl(II) complexes are known for carbon ligands. The chemistry of organothallium(III) compounds is more extensive, encompassing such species as R3Tl, R2TlX, RTlX2 (X = anionic ligand), and complexes of these species with additional ligands. A wide array of X-ray crystal structures for Tl(III) complexes reveals monomeric, oligomeric, and polymeric arrangements, with bridging ligands being very common.

Thallium compounds are highly toxic and should be handled with great care. Volatile Tl species are of use in the chemical-vapor deposition of superconducting phases. Finally, Tl(III) salts are fairly important reagents in organic syntheses, especially in oxidations and in ring expansion and contraction reactions.


  • cyclopentadienyl complexes;
  • metal–metal bonds;
  • metal toxicity;
  • organic synthesis;
  • thallium;
  • X-ray crystallography