Structure and reactivities of rhenium and technetium bis-arene sandwich complexes [M(η 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-arene99 Tc sandwich complexes [99 Tc(η6 -hmbz)(η6 -C6 H5 -NH3 )](PF6 )2 and [99 Tc(η6 -hmbz)(η6 -C6 H5 -Br)](PF6 ). Both comprise functionalities for conjugation to targeting molecules or for being included as substructures in pharmaceutically active lead compounds. Since η6 -benzene ligands are too stably bound to be replaced with incoming ligands, we prepared naphthalene complexes [Re(η6 -C6 H6 )(η6 -napht)]+ and [Re(η6 -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 of99 Tc and Re may lead to a molecule-based theranostic approach.