Reactions of [Re(CO)3]+ with Histidylhistidine and Modified Histidines

Coordination of a bis-histidine-oligopeptide to Re(i) and Ga(iii) in aqueous solution

We have spectroscopically analyzed the chemistry in aqueous solution and the properties of the histidine-based chelator pHis2 complexed to the fac-[Re(H₂O)₃(CO)₃]⁺ and Ga(iii) to unveil the molecular determinants of their coordination.

Tricarbonyltechnetium(I) and tricarbonylrhenium(I) complexes of amino acids: crystal and molecular structure of a novel cyclic dimeric Re(CO)3-amino acid complex comprised of the OON donor atom set of the tridentate ligand

Radiolabeled complexes of monoamino polycarboxylic, polyamino monocarboxylic and thiol containing amino acid ligands were prepared from a fac-[(99m)Tc(CO)3(H2O)3](+) precursor.The overall radiochemical yield was 94-98%. The complexes exhibited substantial in vitro and in vivo stability. The corresponding Re(I) complexes of the ligands DAPA, Asp and CysH were prepared and characterized by means of IR, NMR, and MS spectroscopic studies, as well as X-ray crystallography (for those containing D,L-DAPA and D,L-Asp). The rhenium complexes have been structurally correlated with the technetium complexes by means of HPLC studies. The reaction of Re(CO)5Cl with D,L-Asp in presence of triethylamine led to the formation of a new class of cyclic dimeric complexes formed by the OON donor atom set of the tridentate ligands. The amino carboxylate ligand system formed well defined complexes with a fac-[M(CO)3(H2O)3](+) core and shows good promise in (99m)Tc(CO)3 tracer development.

Synthesis of C2 -Symmetric Dimeric Re(I) Peptide Complexes

The reactions of [Re(CO)₃(H₂O)₃]Br or Re(CO)₅Cl with two peptides, glycylglycine or glycylalanine, were investigated. Each reaction produced a unique, well-defined product. Structural elucidation showed the formation of chiral compounds with the formula [Re(CO)₃(Gly-Xxx-O)]₂, Xxx = Gly 1, Ala 2. Each dimer displays C₂ -symmetry and a nearly rectangular shape. The ligands are bound via the amine and amide carbonyl at a rhenium center and via the pendant carboxylate to the adjacent rhenium center. Both products are fully characterized, via X-ray structure elucidation.

Re(CO)(3)(H(2)O)(3)(+) binding to lysozyme: structure and reactivity

The reaction of Re(CO)(3)(H(2)O)(3)(+) with hen egg white lysozyme in aqueous solution results in a single covalent adduct. Both NMR spectroscopy and single crystal X-ray diffraction show that the rhenium tricarbonyl cation binds to His15 via replacement of one of the coordinated water molecules. The formation of this adduct does not greatly affect the structure of the protein.