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.
