POTENTIAL OF THE [M(CO)(3)](+) (M = RE, TC) MOIETY FOR THE LABELING OF BIOMOLECULES

The synthesis of [MX3(CO)(3)](2-) (M = Re-188, Re, Tc-99) directly fro m the corresponding permetallates is described. Intermediates and bypr oducts have been isolated and characterized. Preliminary direct labeli ng studies at r.t. revealed a slow but irreversible incorporation of ' '[Re-188(CO)(3)](+)'' into intact antibodies. The best yield was 40% a fter 20 h with 0.8 mg/ml of intact antibody. To elucidate possible coo rdination sites in proteins, the synthesis and formation of model comp lexes has been investigated by means of H-1 NMR spectroscopy and X-ray structure analysis. A high tendency for imidazole (im) coordination h as been found and is examplified in the model complexes [ReBr(histamin e)-(CO)(3)] and [Re-2(mu-OH)(2)(im)(2)(CO)(6)], which structures will be presented. Additionally, complexation with the macrocyclic thioethe r ligand [20-aneS6] was studied in order to establish a post-labeling protocol with this type of chelator. The structure of [(20-aneS6-OH){T c(CO)(3)}(2)](2+) will be presented.