Multifunctional cyclopentadiene (Cp) ligands and their rhenium and 99m Tc complexes were prepared by a versatile synthetic route. The properties of these Cp ligands can be tuned on demand, either during their synthesis (variation of R1 ) or through post-synthetic functionalization with two equal or different vectors (V1 and V2 ). Variation of these groups enables a combinatorial approach in the synthesis of bioorganometallic complexes. This is demonstrated by the preparation of Cp ligands containing both electron-donating and electron-withdrawing groups at the R1 position and their subsequent homo- or heterofunctionalization with biovector models (benzylamine and phenylalanine) under standard amide bond-formation conditions. All ligands can be coordinated to the fac-[Re(CO)3 ]+ and fac-[99m Tc(CO)3 ]+ cores to give tetrafunctional complexes in straightforward and functional-group-tolerant procedures. The 99m Tc complexes were prepared in one step, in 30 min, and under aqueous conditions from generator-eluted [99m TcO4 ]- .
Keywords: cyclopentadienyl ligands; rhenium; synthetic methods; technetium; theranostics.
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