Technetium(IV) chloride

Technetium(IV) chloride is the chemical compound composed of technetium and chlorine with the formula TcCl₄. It was discovered in 1957 as the first binary halide of technetium. It is the highest oxidation binary chloride of technetium that has been isolated in the solid-state. It is volatile at elevated temperatures and its volatility has been used for separating technetium from other metal chlorides.[2] Colloidal solutions of technetium(IV) chloride are oxidized to form Tc(VII) ions when exposed to gamma rays. [3]

Technetium(IV) chloride

Names
IUPAC name Technetium(IV) chloride
Other names Technetium tetrachloride, Technetium chloride
Identifiers
CAS Number	14215-13-5^Y
Properties
Chemical formula	TcCl4
Molar mass	239.718 g/mol
Boiling point	300 °C (572 °F; 573 K)[1]
Structure
Crystal structure	Orthorhombic, oP40
Space group	Pbca, No. 61
Lattice constant	a = 0.603 nm, b = 1.165 nm, c = 1.406 nm α = 90°, β = 90°, γ = 90°
Related compounds
Other anions	Technetium(VI) fluoride
Other cations	Manganese(II) chloride Rhenium(V) chloride Ruthenium(III) 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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Infobox references

Technetium tetrachloride can be synthesized from the reaction of Cl₂(g) with technetium metal at elevated temperatures between 300-500 °C:[4]

Tc + 2 Cl₂ → TcCl₄

Technetium tetrachloride has also been prepared from the reaction of ditechnetium heptoxide with carbon tetrachloride in a bomb reaction vessel at elevated temperature and pressure:

Tc₂O₇ + 7 CCl₄ → 2 TcCl₄ + 7 COCl₂ + 3 Cl₂

At 450 °C under vacuum, TcCl₄ decomposes to TcCl₃ and TcCl₂.

Technetium trichloride

Technetium trichloride TcCl₃ was reported in 2010. It was prepared from ditechnetium(III) tetraacetate dichloride and HCl(g) at 300 °C as a black solid. Its structure consists of triangular Tc₃Cl₉ units with C_3V symmetry, with each Tc atom coordinated to two Tc neighbors and five chloride ligands (Tc-Tc bond length 2.44 angstrom). The Tc-Tc distances are indicative of double bonded Tc atoms. Tc₃Cl₉ is isostructural to its rhenium homologue.[5]

References

1. Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
2. Schwochau, Klaus (2000). Technetium. Wiley-VCH. p. 67. ISBN 978-3-527-29496-1.
3. Fattahi, M.; Vichot, L.; Poineau, F.; Houée-Levin, C.; Grambow, B. (2005). "Speciation of technetium(IV) chloride under gamma irradiation". Radiochimica Acta. 93 (7): 409–413. doi:10.1524/ract.2005.93.7.409.
4. Johnstone, Erik V.; Poineau, Frederic; Forster, Paul M.; Ma, Longzou; Hartmann, Thomas; Cornelius, Andrew; Antonio, Daniel; Sattelberger, Alfred P.; Czerwinski, Kenneth R. (2012-07-09). "Technetium Tetrachloride Revisited: A Precursor to Lower-Valent Binary Technetium Chlorides". Inorganic Chemistry. 51 (15): 8462–8467. doi:10.1021/ic301011c. PMID 22775538.
5. Poineau, Frederic; Johnstone, Erik V.; Weck, Philippe F.; Kim, Eunja; Forster, Paul M.; Scott, Brian L.; Sattelberger, Alfred P.; Czerwinski, Kenneth R. (2010). "Synthesis and Structure of Technetium Trichloride". Journal of the American Chemical Society. 132 (45): 15864–5. doi:10.1021/ja105730e. PMID 20977207.