Darstellung und Charakterisierung der Tetrabutylammoniumsalze von [Tc2Cl8]2-, [Tc2Cl8]3- und [Tc2Br8]2- Preparation and Characterization of the Tetrabutylammonium Salts of [Tc2Cl8]2-, [Tc2Cl8]3- und [Tc2Br8]2-

Abstract

The reduction of [TcCl6]2- with Zn in conc. HCl after evaporation and extraction of ZnCl2 by diethylether yields a red-brown product from which after dissolving in dilute HCl by a solution of (TBA)Cl in CH2Cl2 (TBA)2[Tc2Cl8] and (TBA)3[Tc2Cl8] can be extracted. The separation is achieved by the much better solubility of the green (TBA)2[Tc2Cl8] in acetone compared with that of the grey-blue (TBA)3[Tc2Cl8]. On treatment of (TBA)2[Tc2Cl8] dissolved in acetone with bromine-free conc. HBr carmine red (TBA)2[Tc2Br8] is obtained for the first time. The vibrational spectra are similar and can be assigned according to the assumed D4h-symmetry. In the Raman spectra of both octachloroditechnetates the intensive Tc-Tc-vibration (A1g) is observed at 307 cm-1, for (TBA)2[Tc2Br8] it is found at 323 cm-1 . The electronic spectrum of (TBA)2[Tc2Cl8] agrees to a high extent with that of the corresponding Re compound