Technetium trichloride is an inorganic compound of

technetium Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. All available technetium is produced as a synthetic element. Naturally occurring technetium is a spontaneous ...

and

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is ...

with the formula TcCl₃.

Preparation and properties

Two polymorphs of technetium trichloride are known. The α-polymorph is prepared as a black solid from ditechnetium(III) tetraacetate dichloride and

hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride g ...

at 300 °C. It has a bioctahedral structure, consisting 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 In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest ...

2.44

angstrom The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...

). The Tc-Tc distances are indicative of double bonded Tc atoms. Tc₃Cl₉ is isostructural to its rhenium homologue, trirhenium nonachloride. β-TcCl₃ is obtained by the reaction between technetium metal and chlorine gas. Its structure consists of infinite layers of edge-sharing octahedra, similar to MoCl₃ and ReCl₃, with distances that also indicate metal-metal bonding. It is less stable than α-TcCl₃ and slowly transforms into it.

References

{{Chlorides Technetium compounds Metal halides Chlorides