Coordination chemistry with fluorinated chelators and m-terphenyl isocyanides

Abstract

In this thesis, a series of novel fluorinated ligands and corresponding metal complexes is presented. All compounds were spectroscopically and/or crystallographically characterized. The synthesis of a series of differently halogenated S,N,S-tridentate thiosemicarbazone ligands and their Re(V), Tc(V), Au(III) and In(III) complexes is described. The fluorination reduces the stability of the free ligands against hydrolysis but does not influence significantly the structure and stability of the Re, Tc and Au complexes. On the contrary, the structures and properties of the In(III) complexes are affected by fluorination. Some of the compounds were investigated regarding to their biological activity against Trypanosoma cruzi, a parasite responsible for a tropical disease, known as Chagas disease. Subsequently, the synthesis of Re(I) and Tc(I) complexes with fluorinated and non-fluorinated meta- terphenyl isocyanides is described. Reactions of [Re(CO)5Br] and (NBu4)[Tc2(CO)6(μ-Cl)3] with the encumbering isocyanides give stable complexes with a high degree of steric protection, which are suitable starting materials for the formation of highly-reduced and low-coordinated metal species. The reaction of the Re(I) and Tc(I) isocyanide complexes with different reducing agents is reported, leading to defined products containing persistent monomeric Re(0) complexes or rhenium in a negative formal oxidation state. Moreover, the first known complex with Tc in the formal –1 oxidation state was characterized with NMR spectroscopy.