Reaction of Pertechnetate in Highly Alkaline Solution: Synthesis and Characterization of the Nitridotrioxotechnetate Ba[TcO₃N]

Abstract

The preparation of novel technetium oxides, their characterization and the general investigation of technetium chemistry are of significant importance, since fundamental research has so far mainly focused on the group homologues. Whereas the structure chemistry of technetium in strongly oxidizing media is dominated by the TcO 4 ½ � À anion, our recent investigation yielded the new TcO 3 N ½ � 2À anion. Brown single crystals of Ba[TcO 3 N] were obtained under hydrothermal conditions starting from Ba(OH) 2 • 8H 2 O and NH 4 [TcO 4 ] at 200 °C. Ba½TcO 3 N� crystallizes in the monoclinic crystal system with the space group P2 1 /n (a = 7.2159(4) Å, b = 7.8536(5) Å, c = 7.4931(4) Å and β = 104.279(2)°). The crystal structure of Ba½TcO 3 N� consists of isolated TcO 3 N ½ � 2À tetrahedra, which are surrounded by Ba 2 + cations. XANES measurements complement the oxidation state + VII for technetium and Raman spectroscopic experiments on Ba[TcO 3 N] single crystals exhibit characteristic TcÀ O and TcÀ N vibrational modes.

K3[MO4][MO3N] (M=Tc, Re) – Nitridotrioxidorhenate and ‐technetate from Highly Alkaline Media

“…[20] When comparing to the bands occurring in the Raman spectrum of Ba[TcO 3 N], the most prominent ReÀ N vibration occurs at highest wavenumbers, which is 1023 cm À 1 in case of K 3 [ReO 4 ][ReO 3 N]. [7] The vibrations at lower wavenumbers between 383 cm À 1 and 314 cm À 1 are attributed to symmetric and antisymmetric bending modes of K 3 [ReO 4 ][ReO 3 N]. [20] The magnetic properties of a K 3 [ReO 4 ][ReO 3 N] sample, pure on the level of X-ray powder diffraction, was investigated by magnetic susceptibility and magnetization experiments (see Experimental Section).…”

“…[6] Our recent investigations have shown that Ba[Tc VII O 3 N] can be obtained from the reaction of ammonium pertechnetate in Ba(OH) 2 x8H 2 O and water. [7] Frequently, technetium occurs in the oxidation states + 4, + 5 and + 7, with the [Tc VII O 4 ] À anion being the most prominent representative. [8] However, Ba[TcO 3 N] is the first compound exhibiting the nitridotrioxidotechnetate anion [TcO 3 N] 2À .…”

“…[8] However, Ba[TcO 3 N] is the first compound exhibiting the nitridotrioxidotechnetate anion [TcO 3 N] 2À . [7] So far only pertechnetate has been reacted with barium hydroxide, whereas identical approaches with rhenium and manganese did not lead to isostructural anions. [7] Following the exploration of the redox chemistry of pertechnetate in an alkaline medium as barium hydroxide, the focus has now been directed to flux systems with monovalent cations, e. g. potassium hydroxide.…”

“…[7] So far only pertechnetate has been reacted with barium hydroxide, whereas identical approaches with rhenium and manganese did not lead to isostructural anions. [7] Following the exploration of the redox chemistry of pertechnetate in an alkaline medium as barium hydroxide, the focus has now been directed to flux systems with monovalent cations, e. g. potassium hydroxide. Considering ternary potassium oxo-species of all group 7 elements, the number of crystallographically characterized manganates is comparably high.…”

“…Reactions in highly alkaline media have been well established for decades, [2c,d,3,5] however reactions of technetium species in alkaline environment have not been studied extensively [6] . Our recent investigations have shown that Ba[Tc VII O 3 N] can be obtained from the reaction of ammonium pertechnetate in Ba(OH) 2 x8H 2 O and water [7] . Frequently, technetium occurs in the oxidation states +4, +5 and +7, with the [Tc VII O 4 ] − anion being the most prominent representative [8] .…”