Tetrafluoridonitridotechnetate(VI) – Reactions and Structures

Abstract

Dissolution of the polymeric nitridotechnetic(VI) acid in aqueous HF results in the formation of the [TcNF 4 ]anion. The presence of the paramagnetic anion in such solutions can readily be confirmed by EPR spectroscopy. Addition of * Prof. Dr. U. Abram E-Mail: Ulrich.Abram@fu-berlin.de [a]

One Ligand, One Metal, Seven Oxidation States: Stable Technetium Complexes with the “Kläui Ligand”

“…A partial exchange of the donor atoms in the equatorial coordination sphere can clearly be concluded from the decrease in the g 0 ([TcNCl 4 ] − , 2.003; [TcNCl 2 (L OMe ], 1.991) and g ∥ values ([TcNCl 4 ] − , 2.008; [TcNCl 2 (L OMe )], 1.952) and the increase in the 99 Tc hyperfine coupling constants a 0 Tc ([TcNCl 4 ] − , 187 tme· 10 –4 cm –1 ; [TcNCl 2 (L OMe )], 199 × 10 –4 cm –1 ) and A ∥ Tc ([TcNCl 4 ] − , 293 × 10 –4 cm –1 ; [TcNCl 2 (L OMe )], 319 × 10 –4 cm –1 ). Both the g values and the coupling constants in such axially symmetric complexes are roughly correlated to the spin–orbit coupling constants of the donor atoms, as has been shown by a number of previous studies. − …”

Signatures of technetium oxidation states: a new approach

“…4 Technetium compounds in the II and VI oxidation states are relatively rare in literature. 2,3,[8][9][10] In general, studies to identify Tc oxidation states using other techniques often do not probe the Tc oxidation state directly, but rather determine oxidation states based on structure parameters. 2,3,11 A well-defined oxidation state in coordination species is of paramount importance, since ligand atoms can be connected differently to the coordination center, depending on its oxidation state.…”

Technetium Nitrido-Peroxo Complexes: An Unexplored Class of Coordination Compounds

“…Polymeric nitridotechnetic(VI) acid, [ 99g Tc][Tc(N)(OH) 3 ] n , was prepared as described previously by the hydrolysis of Cs 2 [ 99g Tc][Tc(N)Cl 5 ] in water and isolated as a brown precipitate [1,15,16,27]. The brown solid (84 mg, 0.15 mmol) was dissolved in 0.5 mL of 10% w/w H 2 O 2 , followed by the addition of an excess of the ligand L (0.80 mmol) to yield a pale-yellow solution, which was slightly heated at 30 • C for 15 min.…”

“…A higher yield was achieved following another synthetic route originally proposed by Baldas and coworkers [2]. This procedure first required the in situ generation of nitrido pertechnic acid, [ 99m Tc][Tc(N)(OH) 3 ] n , by aqueous hydrolysis of the nitrido complex [ 99g Tc][Tc(N)Cl 5 ] − [15,16]. The subsequent addition of H 2 O 2 led to the formation of an hypothetical nitrido-peroxo technetic acid, which was further reacted with excess of the appropriate amino acid to yield the final substituted complexes [ 99m Tc][Tc(N)(O 2 ) 2 (L)] − (L = deprotonated Pro, Gly and Ala).…”