Tantalum(V) chloride

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Tantalum(V) chloride

Tantalum, Ta;   Chlorine, Cl
Names
IUPAC names Tantalum(V) chloride Tantalum pentachloride
Identifiers
CAS Number	7721-01-9 TaCl5 Y 17499-29-5 Ta2Cl10 N
3D model (JSmol)	Interactive image
ChemSpider	22805
ECHA InfoCard	100.028.869
EC Number	231-755-6
PubChem CID	24394
UNII	9WXV40ZI4M  Y
CompTox Dashboard (EPA)	DTXSID7064780
InChI Key: OEIMLTQPLAGXMX-UHFFFAOYSA-I InChI=1S/5ClH.Ta/h5*1H;/q;;;;;+5/p-5
SMILES Cl[Ta](Cl)(Cl)(Cl)Cl
Properties
Chemical formula	TaCl5
Molar mass	358.213 g/mol
Appearance	white monoclinic crystals [1] [ page needed ][ contradictory ]
Density	3.68 g/cm3
Melting point	216 °C (421 °F; 489 K)
Boiling point	239.4 °C (462.9 °F; 512.5 K) (decomposes)
Solubility in water	reacts
Solubility	chloroform, CCl4
Magnetic susceptibility (χ)	+140.0×10−6 cm3/mol
Structure
Crystal structure	Monoclinic, mS72
Space group	C2/m, No. 12
Thermochemistry
Std molar entropy (S⦵298)	221.75 J K−1 mol−1
Std enthalpy of formation (ΔfH⦵298)	−858.98 kJ/mol
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H314, H335
Precautionary statements	P260, P264+P265, P270, P271, P280, P301+P317, P301+P330+P331, P302+P361+P354, P304+P340, P305+P351+P338, P305+P354+P338, P310, P316, P330, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	3 0 0
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1900 mg/kg (oral, rat)
Safety data sheet (SDS)	External SDS
Related compounds
Other anions	Tantalum(V) fluoride Tantalum(V) bromide Tantalum(V) iodide
Other cations	Protactinium(V) chloride Vanadium(V) chloride Niobium(V) chloride
Related compounds	Vanadium(IV) chloride Tantalum(III) chloride Tantalum(IV) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N  verify  (what is  YN ?) Infobox references

Tantalum(V) chloride, also known as tantalum pentachloride, is an inorganic compound with the formula TaCl₅. It takes the form of a white powder, which is highly sensitive to moisturee. It is synthesised and manipulated under anhydrous conditions, using air-free techniques. ^{[2] [3]}

Structure

TaCl₅ crystallizes in the monoclinic space group C2/m. ^[4] The ten chlorine atoms define a pair of octahedra that share a common edge. The tantalum atoms occupy the centres of the octahedra and are joined by two chlorine bridging ligands. The dimeric structure Ta₂Cl₁₀ is retained in non-complexing solvents and to a large extent in the molten state. In the vapour state, however, TaCl₅ is monomeric. This monomer adopts a trigonal bipyramidal structure, like that of PCl₅. ^{[5] [ page needed ]}

Synthesis

Tantalum pentachloride can be prepared by treating powdered metallic tantalum with chlorine gas at between 170 and 250 °C. This reaction can also be performed using HCl at 400 °C. ^[6]

2 Ta + 5 Cl₂ → 2 TaCl₅

2 Ta + 10 HCl → 2 TaCl₅ + 5 H₂

It can also be prepared by a reaction between tantalum pentoxide and thionyl chloride at 240 °C. ^[3]

Ta₂O₅ + 5 SOCl₂ → 2 TaCl₅ + 5 SO₂

Tantalum pentachloride is commercially available, however samples can be contaminated with tantalum(V) oxytrichloride (TaOCl₃), formed by hydrolysis. Samples contaminated with niobium pentachloride appear yellow. ^[3]

Reactions

TaCl₅ is electrophilic. It forms adducts with a variety of Lewis bases. It serves as a Lewis acid in Friedel-Crafts reactions. ^[7]

Simple adducts

TaCl₅ forms stable complexes with ethers:. ^{[7] [8]}

TaCl₅ + R₂O → TaCl₅(OR₂) (R = Me, Et)

TaCl₅ also reacts with phosphorus pentachloride and phosphoryl chloride, the former as a chloride donor and the latter serves as a ligand, binding through the oxygen: ^[9]

TaCl₅ + PCl₅ → [PCl₄]⁺[TaCl₆]⁻

TaCl₅ + OPCl₃ → [TaCl₅(OPCl₃)]

Tantalum pentachloride reacts with tertiary amines to give adducts: ^[7]

TaCl₅ + 2 R₃N → [TaCl₅(NR₃)]

Chloride displacement reactions

Tantalum pentachloride reacts at room temperature with an excess of triphenylphosphine oxide to give oxychlorides:

TaCl₅ + 3 OPPh₃ → [TaOCl₃(OPPh₃)]_x ...

Hydrolysis, alcoholysis, ammonolysis and related reactions

Anhydrous TaCl₅ (Ta₂Cl₁₀) rapidly (but not violently) hydrolyses in water at room temperature. ^[10]

Tantalum pentachloride reacts with sodium ethoxide to give the pentaethoxide, which also exists as a dimer: ^[11]

5 NaOC₂H₅ + TaCl₅ → Ta(OC₂H₅)₅ + NaCl

A variety of related alkoxides and mixed chloro-alkoxides are known, e.g. Ta(OCH₃)₅ and Ta(OCH₂CH₃)₃Cl₂. ^[7]

Ammonium chloride gives the nitrido complex [TaCl₅N]³⁻. ^[12]

Reduction

Reduction of tantalum(V) chloride gives anionic and neutral clusters including [Ta₆Cl₁₈]⁴⁻ and [Ta₆Cl₁₄](H₂O)₄. ^[13]

References

1. Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, Florida: CRC Press. ISBN   0-8493-0487-3.^{[ page needed ]}
2. Clark, R. J. H.; Brown, D.; Bailar, J. C.; Emeléus, H. J.; Nyholm, Ronald (2013). The Chemistry of Vanadium, Niobium and Tantalum: Pergamon Texts in Inorganic Chemistry. Texts in Inorganic Chemistry (1. Aufl ed.). s.l.: Elsevier Reference Monographs. ISBN   978-1-4831-8170-7.
3. G. Brauer (1963). "Niobium (V) and Tantalum (V) Chlorides". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. pp. 1302–1305.
4. Rabe, Susanne; Müller, Ulrich (2000). "Crystal structure of tantalum pentachloride, (TaCl₅)₂". Z. Kristallogr. - New Cryst. Struct. 215 (1): 1–2. Bibcode:2000ZK....215....1R. doi: 10.1515/ncrs-2000-0102 .
5. Fairbrother, F. (1967). The Chemistry of Niobium and Tantalum . Elsevier.^{[ full citation needed ]}
6. Young, Ralph C.; Brubaker, Carl H. (1952). "Reaction of Tantalum with Hydrogen Chloride, Hydrogen Bromide and Tantalum Pentachloride; Action of Hydrogen on Tantalum Pentachloride". Journal of the American Chemical Society . 74 (19): 4967. Bibcode:1952JAChS..74.4967Y. doi:10.1021/ja01139a524.
7. Hubert-Pfalzgraf, Liliane G. (2005). "Niobium & Tantalum: Inorganic & Coordination Chemistry". Encyclopedia of Inorganic Chemistry. doi:10.1002/0470862106.ia153. ISBN   978-0-470-86078-6.
8. Cowley, A.; Fairbrother, F.; Scott, N. (1958). "The Halides of Niobium (Columbium) and Tantalum. Part V. Diethyl Ether Complexes of the Pentachlorides and Pentabromides; the Solubility of Tantalum Pentaiodide in Ether". J. Chem. Soc. : 3133–3137. doi:10.1039/JR9580003133.
9. Bullock, J. I.; Parrett, F. W.; Taylor, N. J. (1973). "Some Metal Halide–Phosphorus Halide–Alkyl Halide Complexes. Part II. Reactions with Niobium and Tantalum Pentachlorides and Tungsten Hexachloride". J. Chem. Soc., Dalton Trans. (5): 522–524. doi:10.1039/DT9730000522.
10. "Tantalum(V) chloride | Tantalum pentachloride | TaCl5". Ereztech. Retrieved 2025-12-03.
11. Schubert, U. (2003). "Sol–Gel Processing of Metal Compounds". In McCleverty, J. A.; Meyer, T. J. (eds.). Comprehensive Coordination Chemistry II. Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. Vol. 7. Pergamon. pp. 629–656. doi:10.1016/B0-08-043748-6/06213-7. ISBN   978-0-12-409547-2.
12. Berg, Rolf W. (1992). "Progress in Niobium and Tantalum Coordination Chemistry". Coordination Chemistry Reviews. 113: 1–130. doi:10.1016/0010-8545(92)80074-2.
13. Duraisamy, Thirumalai; Hay, Daniel N. T.; Messerle, Louis (2014). "Octahedral Hexatantalum Halide Clusters". Inorganic Syntheses. Vol. 36. pp. 1–8. doi:10.1002/9781118744994.ch1. ISBN   9781118744994.^{[ full citation needed ]}

Further reading

• Ozin, G. A.; Walton, R. A. (1970). "Vibrational Spectra and Structures of the 1:1 Complexes of Niobium and Tantalum, Pentachlorides and Tantalum Pentabromide with Aceto-, Perdeuterioaceto-, and Propionitriles in the Solid and Solution States and a Vibrational Analysis of the Species MX₅, NC·CY₃ (Y = H or D)". J. Chem. Soc. A : 2236–2239. doi:10.1039/j19700002236.
• Đorđević, C.; Katović, V. (1970). "Co-ordination Complexes of Niobium and Tantalum. Part VIII. Complexes of Niobium(IV), Niobium(V), and Tantalum(V) with Mixed Oxo, Halogeno, Alkoxy, and 2,2′-Bipyridyl Ligands". J. Chem. Soc. A : 3382–3386. doi:10.1039/j19700003382.

External links

• NIST Standard Reference Database