AgTcO4 reacts with R3ECl compounds (E = C, Si, Ge, Sn, Pb; R = Me, 'Pr, 'Bu, Ph), 'Bu2SnCl2, or PhMgCl under formation of novel trioxotechnetium(VII) derivatives. The carbon and silicon derivatives readily undergo decomposition, which was proven by Tc-99 NMR spectroscopy and the isolation of decomposition products such as [TcOCl3(THF)(OH2)]. Compounds [Ph3GeOTcO3], [(THF)Ph3SnOTcO3], [(O3TcO)Sn'Bu-2(OH)](2), and [(THF)(4)Mg(OTcO3)(2)] are more stable and were isolated in crystalline form and characterized by X-ray diffraction.