From TcVII to TcI; facile syntheses of bis-arene complexes [99(m)Tc(arene)2]+ from pertechnetate

Bis-arene complexes of technetium represent a fundamental class of organometallic compounds. Due to complex synthetic routes, no detailed insights into their properties have been reported so far. Reacting [(TcO4)-Tc-99](-) with arenes in the exclusive presence of AlCl3 gives highly stable [Tc-99(arene)(2)](+) in good yields. These complexes have extraordinarily high stabilities, where oxidation is found to occur at potentials higher than +1.3 V and reduction at potentials below -2 V vs. Fc/Fc(+). The Tc-99m analogues are similarly synthesised by applying a novel ionic liquid extraction pathway. Complexes of Tc-99m with suitably functionalized arenes will represent new building blocks for bioorganometallic pharmaceuticals in molecular imaging.