Technetium Complexes with Triazacyclononane

[NBu₄][TcOCl₄] reacts with ethylene glycol and 1,4,7-triazacyclononane (tacn) in MeOH under the formation of the deep-blue oxotechnetium(V) cation [TcO(OC₂H₄O)(tacn)]⁺, which can readily be oxidized by air to give the stable technetium(VII) compound [TcO₃(tacn)]⁺. The reaction with aqueous HCl results in reduction and the formation of the cationic technetium(III) complex [TcCl₂(OH₂)(tacn)]Cl. The products were isolated in crystalline form and studied spectroscopically and by X-ray diffraction.