Structure and reactivities of rhenium and technetium bis-arene sandwich complexes [M(?(6)-arene)2]().

Sandwich complexes are important building blocks in medicinal inorganic chemistry for group 6 and 8 elements but are almost unknown for the manganese triad. We present the syntheses and full characterization of the mixed-arene (99)Tc sandwich complexes [(99)Tc(?(6)-hmbz)(?(6)-C6H5-NH3)](PF6)2 and [(99)Tc(?(6)-hmbz)(?(6)-C6H5-Br)](PF6). Both comprise functionalities for conjugation to targeting molecules or for being included as substructures in pharmaceutically active lead compounds. Since ?(6)-benzene ligands are too stably bound to be replaced with incoming ligands, we prepared naphthalene complexes [Re(?(6)-C6H6)(?(6)-napht)](+) and [Re(?(6)-napht)2](+). Their reactivities towards substitution are increased and one or both naphthalene ligands can be replaced with mono- or multi-dentate ligands. Combining the features of (99)Tc and Re may lead to a molecule-based theranostic approach.