Tantalum(III) chloride

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Tantalum(III) chloride
Other names
tantalum trichloride
3D model (JSmol)
ECHA InfoCard 100.033.611 Edit this at Wikidata
EC Number
  • 236-988-7
  • InChI=1S/3ClH.Ta/h3*1H;/q;;;+3/p-3
  • Cl[Ta](Cl)Cl
Molar mass 287.30 g·mol−1
Appearance black-green
Melting point 440 °C (824 °F; 713 K) decomposes[1]
Related compounds
Other anions
Tantalum(III) bromide
Tantalum(III) iodide
Other cations
Niobium(III) chloride
Related compounds
Tantalum(IV) chloride
Tantalum(V) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Tantalum(III) chloride or tantalum trichloride is non-stoichiometric with a range of composition from TaCl2.9 to TaCl3.1[2] Anionic and neutral clusters containing Ta(III) chloride include [Ta6Cl18]4− and [Ta6Cl14](H2O)4.[3]

Structure of edge-capped octahedral clusters such as Ta6Cl182−.[4]


Tantalum(III) chloride is formed by reducing tantalum(V) chloride with tantalum metal. this is done by heating tantalum(III) chloride to 305 °C, passing the vapour over tantalum foil at 600°, and condensing the trichloride at 365 °C. If the condensing region is kept at too high a temperature, then TaCl2.5 deposits instead.[5]

The trichloride can also be prepared by thermal decomposition of TaCl4, with removal of volatile TaCl5. TaCl5 can be vapourised leaving behind TaCl3.[6]

"Salt-free reduction" of a toluene solution of TaCl5 with 1,4-disilyl-cyclohexadiene in the presence of ethylene produces a complex of TaCl3:[7]

TaCl5 + C6H6(SiMe)2 → TaCl3 + C6H6 + 2 Me3SiCl


Above 500 °C, TaCl3 disproportionates further releasing TaCl5.[6] TaCl3 is insoluble in room temperature water, or dilute acid, but dissolves in boiling water. A blue-green solution is formed.[6]


Tantalum(III) chloride can form complexes with some ligands as a monomer or dimer.

Complexes include Ta(=C-CMe3)(PMe3)2Cl3, [TaCl3(P(CH2C6H5)3THF]2μ-N2 and [TaCl3THF2]2μ-N2 (dinitrogen complexes).[8]

As a dimer, complexes include Ta2Cl6(SC4H8)3 (SC4H8=tetrahydrothiophene). Ta2Cl6(SMe2)3, Ta2Cl6(thiane)3 and Ta2Cl6(thiolane)3 have a double bond between the two tantalum atoms, and two bridging chlorides, and a bridging ligand.[7]


  1. ^ Haynes, William M. (2016). CRC Handbook of Chemistry and Physics (97 ed.). CRC Press. pp. 4–97. ISBN 978-1-4987-5429-3.
  2. ^ Cotton, F Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry A Comprehensive Text. John Wiley. p. 927.
  3. ^ Duraisamy, Thirumalai; Hay, Daniel N. T.; Messerle, Louis (2014). "Octahedral Hexatantalum Halide Clusters". Inorganic Syntheses: Volume 36. Inorganic Syntheses. Vol. 36. pp. 1–8. doi:10.1002/9781118744994.ch1. ISBN 9781118744994.
  4. ^ Thaxton, C. B.; Jacobson, R. A. (1971). "The Crystal Structure of H2(Ta6Cl18)(H2O)6". Inorganic Chemistry. 10: 1460–1463. doi:10.1021/ic50101a029.{{cite journal}}: CS1 maint: uses authors parameter (link)
  5. ^ Gutmann, Viktor (2012). Halogen Chemistry. Elsevier. p. 158. ISBN 978-0-323-14847-4.
  6. ^ a b c Remy, Heinrich (1963). Treatise on Inorganic Chemistry: Sub-groups of the periodic table and general topics. Elsevier Publishing Company. p. 115.
  7. ^ a b Tsurugi, Hayato; Mashima, Kazushi (2019). "Salt-Free Reduction of Transition Metal Complexes by Bis(trimethylsilyl)cyclohexadiene, -dihydropyrazine, and -4,4′-bipyridinylidene Derivatives". Accounts of Chemical Research. 52 (3): 769–779. doi:10.1021/acs.accounts.8b00638. PMID 30794373. S2CID 73505603.
  8. ^ Churchill, Melvyn Rowen.; Wasserman, Harvey J. (1982). "The Ta(μ-N2)Ta System. 2. Crystal Structure of [TaCl3(P(bz)3)(THF)]2(μ-N2).≈0.7CH2Cl2. A Binuclear Di-imido Complex of Octahedral Tantalum(V)". Inorganic Chemistry. 21 (1): 218–222. doi:10.1021/ic00131a040.