Neutral oxorhenium(V) and oxotechnetium(V) complexes with novel amide thioether dithiolate ligands derived from cysteine

Abstract

Oxo complexes / Rhenium and technetium complexes / Thioether/amide ligand / Crystal structuresSummary. Bifunctional ligands able to form neutral complexes with radioactive technetium and rhenium and to couple to biological relevant anchor groups play an important role in the design of new radiopharmaceuticals for diagnosis and therapy. A novel tetradentate amide thioether dithiolate ligand HS−CH 2 CH 2 −S−CH 2 CONH−CH(COOR)CH 2 SH (H 3 SNSS) with R = CH 3 , C 10 H 21 was synthesized that forms stable complexes with technetium and rhenium in oxidation state V. The molecular structures of the rhenium and technetium complexes MO(SNSS) were determined by X-ray structural analysis and show that the metal coordination number is five and the coordination polyhedron is between square-pyramidal and trigonal-bipyramidal. The pendent ester group allows coupling of the chelate unit at biologically relevant anchor groups. As a relevant representative the X-ray structural analysis of the rhenium decylester complex was carried out. The complex formation with Tc at the n.c.a. level and 186 Re at 10 −6 M level is described.

Assessment of density functional methods for the study of vanadium and rhenium complexes with thiolato ligands

“…The electronic structure of the center {VOS 4 } in [VO(bdt) 2 ] 2À (bdt 2À = 1,2-benzenedithiolato) has been studied by Cooney et al [14], providing valuable background information regarding the mode-of-action of vanadium-containing nitrate reductase (V-NR), analogous to molybdenum-containing bacterial NR. Oxocomplexes of rhenium(V) containing dithiolato ligands have been attracted attention due to their role in oxygen atom transfer reactions (OAT) [15][16][17], and because the nuclear properties of 186 Re and 188 Re, as a potential radiopharmaceuticals, not only for diagnosis but also for therapeutic purposes [18,19].…”

Synthesis, Characterization, and In Vitro Evaluation of New 99mTc/Re(V)-Cyclized Octreotide Analogues: An Experimental and Computational Approach

“…48−51 In addition, it has been reported that 99g Tc complexes and their Re surrogates with almost identical crystal structures can exhibit different elution behavior. 52,53 Although the mechanism behind this observation remains unclear, the substitution inertness of Re complexes compared to 99g/99m Tc complexes is believed to play an important role. 52 Because a 0.4 to 1.1 min difference in retention times between the corresponding 99m Tc-and Re-SDPhe-TATE isomers was observed, we are unable to conclude whether 99m Tc is coordinated to SDPhe-TATE identically to Re, based on the current experimental data.…”

“…Characterization of 99m Tc complexes is often accomplished by chromatographic correlation with the corresponding Re complexes. ,− Although in some cases coelution was observed upon HPLC analysis, ,, in other cases the retention times of the 99m Tc complexes were found to differ by approximately half a minute to 2 min, which has not always been noted in the literature. − In addition, it has been reported that 99g Tc complexes and their Re surrogates with almost identical crystal structures can exhibit different elution behavior. , Although the mechanism behind this observation remains unclear, the substitution inertness of Re complexes compared to 99 g /99m Tc complexes is believed to play an important role . Because a 0.4 to 1.1 min difference in retention times between the corresponding 99m Tc- and Re-SDPhe-TATE isomers was observed, we are unable to conclude whether 99m Tc is coordinated to SDPhe-TATE identically to Re, based on the current experimental data.…”

27 Radiochemistry and radiopharmaceuticals

“…The radiochemical purity of 123 I produced by the proton irradiation of 124 Xe has been shown to be an order of magnitude better 182 than that produced by similar irradiation of natural iodine, in the former case the level of 125 I contamination is about 0.01%.…”

“…For example, the proposed central nervous system imaging agents often utilized piperizine derivatives and thiols, 120,121 thiocresols 122 or related molecules. Similar ligands have been used in making new complexes based on oxy-technetium(V) which can then be used to label derivatives of cysteine 123 or serotonin 5-HT1A brain receptors. 124,125 Following the '3 + 1' idea many new technetium complexes have been based 126 on the hydrated tricarbonyl fragment.…”