The Synthesis of Novel „4+1” Tc(III)/Re(III) Mixed-ligand Complexes with a Dendritic Modified Monodentate Ligand

Inert, so-called “4+1” trigonal-bipyramidal coordinated mixed–ligand complexes of the trivalent technetium and rhenium with tetradentate and monodentate ligands proved to be more stable than the pentavalent “3+1” mixed–ligand complexes with the (M=O)3+ core. They have appeared not to undergo a substitution in vivo with SH groups of such species as cysteine or glutathione [1].
In the presented paper we describe the synthesis of novel 99mTc(III) and 188Re(III) complexes containing the tripodal chelator 2,2’,2’’-nitrilotris(ethanethiol), NS3, and a dendritic modified monodentate isocyanide, CN-R(den). The reaction course was monitored with TLC and the radiochemical purity was monitored by HPLC. As a reference compound we have synthesized also the non-radioactive rhenium(III) complex which has been characterized by elemental analysis, IR, MS, 1H and 13C NMR.