The fixation of linear versus loop-type peptidic structures by metal coordination: the coordination chemistry of Val–Val- and Val–Val–Val-bridged dicatechol ligands

Abstract

The Val–Val-bridged dicatechol ligand L¹-H₄ forms triply-bridged dinuclear complexes with titanium(IV) ions, while the more flexible Val–Val–Val derivative L²-H₄ leads to mixtures of complexes containing species with a cyclic arrangement of the ligand; with [cis-MoO₂]²⁺ on the other hand, a well-defined macrocycle [(L²)MoO₂]²⁻ is formed which possesses a loop-type structure in the peptidic part of the ligand.