Technetium metal, preparation

Boyd Chemistry of Technetium. II. Preparation of Technetium metal. J. Amer. chem. Soc. 74, 1852 (1952). 

Preparation. It can be made by the irradiation of molybdenum targets with deuterium nuclei. Technetium metal may be easily prepared by reduction of NH4Tc04 (or TcC>2) with hydrogen or by electrodeposition from an NH4Tc04 solution. 

Pure technetium metal may he prepared hy reducing ammonium pertech-nate, NH4TCO4, with hydrogen at high temperatures. Hydrogen reduction at about 200°C first forms the oxide, Tc02, which is reduced to Tc metal at 600 to 800°C. 

Binary metal carbonyl complexes, with technetium, 5, 835 Binary technetium isocyanides, preparation and properties,... 

Technetium(VII) oxide is a yellow solid, crystallizing in the orthorhombic space group D2)l15-Pbca and is one of the few known transition metal oxides having a molecular structure in the solid state.10 It melts at 119.5° and boils at 310.6° It dissolves in water, forming pertechnetic acid. The pertechnetate ion is known to inhibit the corrosion of steel. TechnetiumfVII) oxide is an excellent starting material for preparing pure technetium metal. 

Several phosphides of technetium were prepared by reaction of technetium metal powder with red phosphorus at 1220 K using the tin-flux technique or iodine as a mineralizer. The preparation was carried out in evacuated, sealed silica tubes. 

Technetium hexafluoride can be prepared by reaction of technetium metal powder with excess fluorine gas in a closed nickel can at 400 °C. The volatile golden-yellow solid was purified by fractional sublimation at reduced pressure. The yield of purified TcF, was greater than 90% [63[. Lower conversions are obtained by treating finely divided technetium metal at 350 °C with a F2/N2 mixture in a flow stream. TcFf, melts at 37.4 °C, boils at 55.3 °C, and undergoes a solid-solid transition at -4.54 °C from the low temperature orthorhombic to the bcc modification at room temperature [64]. More recently the transition temperature of 268.335 K was reported [67]. 

The structure of a rhenium(V) complex with l,3,5-trideoxy-l,3,5-tris (2-hydroxybenzylamino)-c /i -inositol has been described, and the metal ion sequestering abilities of borate esters of 2-amino-2-deoxy-D-gluconate and 2-amino-2-deoxy-D-galactonate have been studied. The largest effects were measured upon adding Cd(ll) or Ni(II) to the borate - 2-amino-2-deoxy-D-gluconate system. A ribonucleoside technetium chelate prepared from 2, 3 -diamino-2, 3 -dideoxyadenosine is mentioned in Chapter 20. 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

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