Technetium Compounds

Technetium Dichloride: A New Binary Halide Containing Metal–Metal Multiple Bonds

“…This observation is likely due to steric effects, which will be more pronounced in the eclipsed conformation. The metal–metal separation in TcCl 2 is similar to that observed in a number of Tc(II) dimers and consistent with the presence of a metal–metal triple bond, which would make it the highest bond multiplicity reported so far in a binary halide . Further evidence for triple bonds in TcCl 2 is provided by first-principles calculations of the natural bond orbital (NBO) occupancy of the Tc–Tc bond, NBO = 5.30, i.e., close to a perfect triple covalent bond (NBO = 6.00) .…”

“…We believe the “TcCl 2 structure type” is likely to be encountered for other metals which are known to form molecular complexes containing metal–metal bonded M 2 X 8 units (e.g., M = Mo, W, Re, Os; X = Cl, Br, I). In this context, we note that β-MoCl 2 , ReI 2 , and OsI 2 have been reported, but their solid state structures are currently unknown. , For technetium, two [Tc 2 Br 8 ] n − ( n = 2, 3) ions have been reported and TcBr 2 may be accessible using a bromine variant of the reaction reported here for TcCl 2 . Although further experimentation is needed, TcCl 2 , because of its insolubility in aqueous media, holds promise as a waste storage form.…”

“…Technetium dichloride is the first transition metal binary halide reported to date with a prismatic, M–M bonded M 2 X 8 unit. The [Tc 2 Cl 8 ] unit exhibits an eclipsed conformation similar to the one found in the [Tc 2 Cl 8 ] n − ( n = 2, 3) ions . The conformation of the [Tc 2 Cl 8 ] unit in TcCl 2 differs from the one found in the salt K 2 Tc 2 Cl 6 .…”

Technetium: The First Radioelement on the Periodic Table

“…Technetium exhibits extensive redox chemistry with 9 oxidation states ranging from −1 to +7, where technetium complexes with the metal atom in valence +7 to +3 are often used as precursors in synthetic chemistry . However, due to its radioactivity and late discovery, there is relatively little known about its chemistry in comparison with the neighboring stable elements. − …”

Synthetic and Coordination Chemistry of the Heavier Trivalent Technetium Binary Halides: Uncovering Technetium Triiodide

“…In the past 5 years, the chemistry of technetium binary halides has experienced rapid development and five new phases were reported, which brings the total number of known technetium binary halides to eight. These include two fluorides (TcF 6 and TcF 5 ), four chlorides (TcCl 4 , α/β-TcCl 3 , and TcCl 2 ), and two bromides (TcBr 4 and TcBr 3 ). − Trivalent technetium halides have a rich chemistry, and three phases have been reported: TcBr 3 , α-TcCl 3 , and β-TcCl 3 . − These phases exhibit various dimensionalities and consist of either clusters or infinite chains and layers of TcX 6 (X = Cl, Br) octahedra (Chart ).…”