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

• Published in: Chemistry : a European journal 2022-11, Vol.28 (63), p.e202201738-n/a
• Main Authors: Badea, D., Dardenne, K., Polly, R., Rothe, J., Hanrath, M., Reimer, M., Meerholz, K., Neudörfl, J.‐M., Strub, E., Bruns, J.
• Format: Article
• Language: English
• Subjects: Anions; Barium hydroxide; Cations; Chemistry; Crystal structure; Crystals; hydrothermal; Oxidation; oxoanions; Single crystals; Technetium; Tetrahedra; Valence; Vibration mode; X-ray; XANES
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202201738

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 TcO4- ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 4}}}\right]}^{-}}$ anion, our recent investigation yielded the new TcO3N2- ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N}}\right]}^{{\rm { 2}}-}}$ anion. Brown single crystals of Ba[TcO3N] were obtained under hydrothermal conditions starting from Ba(OH)2 ⋅ 8H2O and NH4[TcO4] at 200 °C. Ba[TcO3N] ${{\rm { Ba[Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N]}}}$ crystallizes in the monoclinic crystal system with the space group P21/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 Ba[TcO3N] ${{\rm { Ba[Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N]}}}$ consists of isolated TcO3N2- ${{\left[{\rm { Tc}}{{\rm { O}}}_{{\rm { 3}}}{\rm { N}}\right]}^{{\rm { 2}}-}}$ tetrahedra, which are surrounded by Ba2+ cations. XANES measurements complement the oxidation state +VII for technetium and Raman spectroscopic experiments on Ba[TcO3N] single crystals exhibit characteristic Tc−O and Tc−N vibrational modes. Hot chemistry. The nitridotrioxotechnetate anion has been obtained by the reaction of ammonium pertechnetate under highly alkaline conditions. In addition to a single crystal structure analysis, Raman data proves the existence of Tc−O and Tc−N bonds. The oxidation state +VII has further been corroborate by XANES and EXAFS measurements.