Technetium(IV) chloride explained

Technetium(IV) chloride is the inorganic compound 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 as a solid. It is volatile at elevated temperatures and its volatility has been used for separating technetium from other metal chlorides.^[1] Colloidal solutions of technetium(IV) chloride are oxidized to form Tc(VII) ions when exposed to gamma rays.^[2]

Technetium tetrachloride can be synthesized from the reaction of Cl₂ with technetium metal at elevated temperatures between 300 and 500 °C:^[3]

Tc + 2 Cl₂ → TcCl₄

Technetium tetrachloride has also been prepared from the reaction of technetium(VII) oxide with carbon tetrachloride in a sealed vessel at elevated temperature:^[4]

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

At 450 °C under vacuum, TcCl₄ decomposes to TcCl₃ and TcCl₂.^[5]

As verified by X-ray crystallography, the compound is an inorganic polymer consisting of interconnected TcCl₆ octahedra.

Notes and References

1. Book: Schwochau , Klaus . 2000. Technetium. Wiley-VCH. 978-3-527-29496-1. 67.
2. Fattahi. M.. Vichot. L.. Poineau. F.. Houée-Levin. C.. Grambow. B.. Speciation of technetium(IV) chloride under gamma irradiation. Radiochimica Acta. 93. 7. 409–413. 2005. 10.1524/ract.2005.93.7.409 . 96640348.
3. 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. EN. 51. 15. 8462–8467. 10.1021/ic301011c. 22775538. 1307429.
4. Book: Housecroft, Catherine E. . Sharpe . A. G. . Inorganic chemistry . Pearson Prentice Hall . Upper Saddle River, N.J. . 2005 . 0-13-039913-2 . 56834315. 669.
5. 10.1021/ar400225b. Recent Advances in Technetium Halide Chemistry. 2014. Poineau. Frederic. Johnstone. Erik V.. Czerwinski. Kenneth R.. Sattelberger. Alfred P.. Accounts of Chemical Research. 47. 2. 624–632. 24393028.