Technetium, fluoride

Calculations suggest TcFy might be prepared S. Riedel, M. Renz and M. Kaupp (2007) Inorg. Chem., vol. 46, p. 5734 - High-valent technetium fluorides. Does TcF exist . 

The use of a special microtechnique has permitted the precipitation, weighing, and determination of about 2 /xg of technetium with a standard deviation of 0.08 /xg . The precipitate is filtered, washed with ice-cold water, dried at 110 °C and weighed as (CgH5) AsTcO. Permanganate, perchlorate, periodate, iodide, fluoride, bromide, thiocyanate anions and mercury, bismuth, lead, silver, tin and vanadyl cations as well as nitrate concentrations above 0.5 M interfere with the determination. 

Most chemical properties of technetium are similar to those of rhenium. The metal exhibits several oxidation states, the most stable being the hep-tavalent, Tc +. The metal forms two oxides the black dioxide Tc02 and the heptoxide TC2O7. At ambient temperature in the presence of moisture, a thin layer of dioxide, Tc02, covers the metal surface. The metal burns in fluorine to form two fluorides, the penta- and hexafluorides, TcFs and TcFe. Binary compounds also are obtained with other nonmetaUic elements. It combines with sulfur and carbon at high temperatures forming technetium disulfide and carbide, TcS2 and TcC, respectively. 

Although the number of tetrafluorides reported is as large as the number of di- and trifluorides (see Table III), this group of compounds is the least well characterized structurally of the transition metal fluorides. The synthesis of most of the expected tetrafluorides has been reported, with examples from titanium to manganese in the first, from zirconium to palladium (except for technetium) in the second, and from hafnium to platinum (except for tantalum) in the third series. Many of them have been little studied and, in general, they have not proved amenable to crystallographic structural analysis. 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

Fluorination and Sorption of Technetium on Magnesium Fluoride Trace quantities of technetium will accompany the... 

A total of 13 batch fluorination-sorption runs were made in this study with fluorine concentrations of 33 and 100%. The fluorination reactor bed temperature was maintained at 500°C and the MgF sorption reactor temperature was maintained at 100°C in each run. When the auxiliary reactor was used, fluorine was added between the fluorinator and the auxiliary reactor to provide a minimum of 15% excess fluorine. The auxiliary reactor temperature was controlled at 500°C. Magnesium fluoride which was preconditioned with fluorine at 400-550°C and at 100 to 125°C was tested during these runs. The MgF treated at the lower temperature was more effective for technetium removal. 

Technetium dioxide trifluoride was recently synthesized by reaction of TC2O7 and XeFh in a 1 3 molar ratio in anhydrous hydrogen fluoride solution via the fluorination... 

In the reaction of technetium metal with chlorine trifluoridc at 650 °C, the mixed oxide fluoride chloride molecules TCOF2CI and TCOFO2 were recently identified by mass spectrometry, in addition to already known technetium oxide fluorides and oxide chlorides [87],... 

The nitrogen analogs of the well-known [TCOX4]" anions mentioned above are technetium(VI) species [TcNX4]". The chlorides in [TcNC ]" are labile, being easily and quickly replaced by bromide " or by fluoride. " There is some qualitative information on the conversion of [TcNCU]" into [Tc04], whose mechanism involves both substitution and electron transfer. " ... 

Radiopharmacy is a discipline concerned with the preparation and quality control of radiopharmaceuticals. The term radiopharmacy is also used for the pharmacy where these activities are carried out Radiopharmaceuticals are medicinal products that contain radionuclides (radioactive isotopes). Radionuclides are produced in nuclear reactors or in cyclotrons. The most important radionuclides used in nuclear medicine are technetium and fluoride. 

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