Tantalum(V) chloride
Names | |
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IUPAC names
Tantalum(V) chloride
Tantalum pentachloride | |
Identifiers | |
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3D model (
JSmol ) |
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ChemSpider | |
ECHA InfoCard
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100.028.869 |
EC Number |
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PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
TaCl5 | |
Molar mass | 358.213 g/mol |
Appearance | white monoclinic crystals[1]
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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) |
reacts | |
Solubility | chloroform, CCl4 |
+140.0×10−6 cm3/mol | |
Structure | |
Monoclinic, mS72
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C2/m, No. 12 | |
Thermochemistry | |
Std molar
entropy (S⦵298) |
221.75 J K−1 mol−1 |
Std enthalpy of (ΔfH⦵298)formation |
-858.98 kJ/mol |
Hazards | |
GHS labelling: | |
Danger | |
H302, H314 | |
P280, P305+P351+P338, P310 | |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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1900 mg/kg (oral, rat) |
Safety data sheet (SDS) | External SDS |
Related compounds | |
Other anions
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Tantalum(V) fluoride Tantalum(V) bromide Tantalum(V) iodide |
Other cations
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Vanadium(IV) chloride
Niobium(V) chloride |
Related compounds
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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).
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Tantalum(V) chloride, also known as tantalum pentachloride, is an
Structure
TaCl5 crystallizes in the
Physical Properties
The solubility of tantalum pentachloride increases slightly for the following series of
- benzene < toluene < m-xylene < mesitylene
This is reflected in the deepening of colour of the solutions from pale yellow to orange. Tantalum pentachloride is less soluble in
Synthesis
Tantalum pentachloride can be prepared by reacting powdered metallic tantalum with chlorine gas at between 170 and 250 °C. This reaction can also be performed using HCl at 400 °C.[4]
- 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
- Ta2O5 + 5 SOCl2 → 2 TaCl5 + 5 SO2
Tantalum pentachloride is commercially available, however samples can be contaminated with tantalum(V)
Reactions
TaCl5 is
Simple adducts
TaCl5 forms stable complexes with
- TaCl5 + R2O → TaCl5(OR2) (R = Me, Et)
TaCl5 also reacts with
- TaCl5 + PCl5 → [PCl+
4][TaCl−
6] - TaCl5 + OPCl3 → [TaCl5(OPCl3)]
Tantalum pentachloride reacts with
- 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 ...
The presumed initial formation of adducts between TaCl5 and hydroxyl compounds such as
- TaCl5 + 3 HOEt → TaCl2(OEt)3 + 3 HCl
In the presence of ammonia as a HCl acceptor, all five chloride ligands are displaced with formation of Ta(OEt)5. Similarly TaCl5 reacts with lithium methoxide in anhydrous methanol to form related methoxy derivatives:
- TaCl5 + 4 LiOMe → Ta(OMe)4Cl + 4 LiCl
- TaCl5 + 5 LiNMe2 → Ta(NMe2)5
With alcohols, the pentachloride reacts to give alkoxides. As shown for the preparation of tantalum(V) ethoxide, such reactions are often conducted in the presence of base:
- 10 EtOH + Ta2Cl10 + 10 NH3 → Ta2(OEt)10 + 10 NH4Cl
Tantalum pentachloride is reduced by nitrogen heterocycles such as pyridine.
Reduction
Reduction of tantalum(V) chloride gives anionic and neutral clusters including [Ta6Cl18]4− and [Ta6Cl14](H2O)4.[6]
References
- ISBN 0-8493-0487-3.
- .
- ^ F. Fairbrother (1967). The Chemistry of Niobium and Tantalum. Elsevier.
- .
- ^ F. A. Cotton, G. Wilkinson, Advanced Inorganic Chemistry (4th ed.), Wiley, New York, 1980.
- ISBN 9781118744994.
- .
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)". .
- 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". .
- 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". .
- 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". .