Preparation and characterization of novel mixed-ligand oxorhenium(V) and oxotechnetium(V) complexes bearing up to four ester groups

The preparation and characterization of three series of novel Re and 99mTc complexes are described. Series I contains complexes with mercaptocarboxylic acids and esters such as mercaptoacetic acid or its ethyl ester and mercaptopropionic acid or its ethyl ester, which also served as precursors for preparing mixed-ligand complexes with dimercaptocarboxylic acids or their esters (series II). Series III includes mixed-ligand complexes with various dimercapto ligands containing a different number of ester moieties. The species formed were analysed by HPLC and MS and are needed for the study of the influence on enzymatic hydrolysis of the number and position of ester and free carboxylic groups in the ligands and the structure of the ligand molecules themselves.