Abstract: “2+1B” tricarbonyl complexes of the general formula [M(CO)3(N^N)CN(CH2)4CH(COOMe)SC10H21]-ClO4, where M = 99mTc or Re, N^N = 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen), were prepared by the reaction of [M(CO)3(N^N)(MeOH)]ClO4 with methyl 2-(decylthio)-6-isocyanohexanoate in methanol. The rhenium complexes were isolated and characterized by 1H NMR and IR spectroscopy. The formation of technetium-99m complexes was confirmed by HPLC. The lipophilicity of the technetium complexes was measured. © Pleiades Publishing, Ltd. 2023.