From Tc(VII) to Tc(I); 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 [(99)TcO(4)](–) with arenes in the exclusive presence of AlCl(3) gives highly stable [(99)Tc(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 (99m)Tc analogues are similarly synthesised by applying a novel ionic liquid extraction pathway. Complexes of (99m)Tc with suitably functionalized arenes will represent new building blocks for bioorganometallic pharmaceuticals in molecular imaging.