A mono-diazenide complex from perrhenate: Toward a new core for rhenium radiopharmaceuticals

Abstract

A new method for the synthesis of low to intermediate oxidation state rhenium complexes containing a bifunctional ligand has been developed. Reaction of [ReO4]- with substituted phenylhydrazines and triphenylphosphine in acetonitrile in the presence of HCl allows the isolation of [ReCl2(NNC6H4-4-R) (NCCH3)(PPh3)2] (where R = OCH3, Cl, or CO2CH3). The substituted hydrazine acts as both a reductant and source of a monodentate diazenide ligand. The compounds have all been characterized in the solid state by X-ray crystallography and in the solution state by NMR, electrospray mass spectrometry, and HPLC. Cyclic voltammetry measurements show that the mono-diazenide complexes undergo a reversible ..