Reactivity of the [M(PS)2]+Building Block (M = ReIIIand99mTcIII; PS = Phosphinothiolate) toward Isopropylxanthate and Pyridine-2-thiolate

none4The coordination properties of isopropylxanthate (i-Pr-Tiox) and pyridine-2-thiolate (PyS) toward the [M(PS)(2)](+) moiety (M = Re and Tc-99m; PS = phosphinothiolate) were investigated. Synthesis and full characterization of [Re(PS2)(2)(i-Pr-Tiox)] (Re1), [Re(PSiso)(2)(i-Pr-Tiox)] (Re2), [Re(PS2)(2)(PyS)] (Re3), and [Re(PSiso)(2)(PyS)] (Re4), where PS2 = 2-(diphenylphosphino)ethanethiolate and PSiso = 2-(diisopropylphosphino)ethanethiolate, and the structural X-ray analysis of complex Re3 were carried out. Tc-99m analogues of complexes Re2 ((99m)Tc2) and Re4 ((99m)Tc4) were obtained in high radiochemical yield following a simple one-pot procedure. The chemical identity of the radiolabeled compounds was confirmed by chromatographic comparison with the corresponding rhenium complexes and by dual radio/UV HPLC analysis combined with ESI(+)-MS of 99g/Tc-99m complexes prepared in carrier-added conditions. The two radiolabeled complexes were stable with regard to trans chelation with cysteine, glutathione, and ethylenediaminotetraacetic acid and in rat and human sera. This study highlights the substitution-inert metal-fragment behavior of the [M(PS)(2)](+) framework, which reacts with suitable bidentate coligands to form stable hexacoordinated asymmetrical complexes. This feature makes it a promising platform on which to develop a new class of Re/Tc complexes that are potentially useful in radiopharmaceutical applications.noneNicola Salvarese;Alessandro Dolmella;Fiorenzo Refosco;Cristina BolzatiSalvarese, Nicola; Dolmella, Alessandro; Fiorenzo, Refosco; Cristina, Bolzat

Electrochemistry of rhenium(V) complexes with bidentate-bidentate and tridentate-bidentate schiff base ligands

The cathodic and anodic behaviour of rhenium(V) complexes, characterized by the ReO3+ core, with bidentate and tridentate Schiff base ligands, has been studied in acetonitrile solvent. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed to define the electrode processes. Electrolyses were also carried out with the aim to identify the nature of the reduced and oxidized products. In particular, it was possible to isolate and characterize new rhenium(VI) complexes, containing the group ReO4+, and the possibility of obtaining stable rhenium(IV) complexes has also been proved

Electrochemistry of rhenium(V) complexes with N-(2-hydroxyphenyl)salicylideneiminate as schiff base ligand

The anodic and cathodic behaviour of the rhenium(V) complexes nBu4N[ReOCl3(HOPhSal)], nBu4N[ReOCl2(OPhSal)], [ReOCl(OPhSal)(MeOH)] and [ReOCl(OPhSal)(PMe2Ph)] in acetonitrile was studied using platinum and mercury electrodes. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed. The nature of the electrolysis products as well as the mechanisms of the electrode oxidation and reduction processes were investigated. In particular a complex of rhenium(VI) containing the group ReO4+ and complexes of rhenium(IV) with ReO2+ core were electrochemically synthesized. They were characterized by elemental analysis, IR spectroscopy, magnetic susceptibility and conductivity measurements

Method for labeling of sensitive and thermosensitive targeting biomolecules with technetium based compounds

The present invention relates to a labeling procedure for the incorporation, in mild reaction conditions, of sensitive and thermosensitive targeting molecules into a [99m Tc(N)(PNP)]-based compound suitable for a kit formulation

Synthesis and characterization of rhenium(III) complexes with (Ph2PCH2CH2)2NR diphosphinoamine ligands

The synthesis and characterization of a new series of neutral, six-coordinated compounds [ReIIIX3(PNPR)], where X is Cl or Br and PNPR is a diphosphinoamine having the general formula (Ph2PCH2CH2)2NR (R = H, CH3, CH2CH3, CH2CH2CH3, CH2CH2CH2CH3 and CH2CH2OCH3) are reported. Stable [ReIIIX3(PNPR)] complexes were synthesized, in variable yields, starting from precursors where the metal was in different oxidation states (iii and v), by ligand-exchange and/or redox-substitution reactions. The compounds were characterized by elemental analysis, proton NMR spectroscopy, cyclic voltammetry, UV/vis spectroscopy, positive-ion electrospray ionization mass spectrometry (ESI(+)-MS) and X-ray diffraction analysis. Although the formulation of the complexes allows either meridional or facial isomers, the latter arrangement was prevalent both in the solid and solution states. Only [ReCl3(PNPH)] showed a meridional configuration both in solution and in the crystalline state. [ReBr3(PNPme)] prefers the meridional configuration in the crystalline state and the facial one in solution. While ESI(+)-MS and voltammetric data seem to indicate some dependency from the nature of the alkyl substituent at the nitrogen, the available structural data of the complexes show only slight differences both for angles and bond lengths upon change of the alkyl chain tethered to the nitrogen

Reactivity of the [M(PS)₂]⁺ Building Block (M = Re^III and ^99mTc^III; PS = Phosphinothiolate) toward Isopropylxanthate and Pyridine-2-thiolate

The coordination properties of isopropylxanthate (<i>i</i>-Pr-Tiox) and pyridine-2-thiolate (PyS) toward the [M­(PS)₂]⁺ moiety (M = Re and ^99mTc; PS = phosphinothiolate) were investigated. Synthesis and full characterization of [Re­(PS2)₂(<i>i</i>-Pr-Tiox)] (<b>Re1</b>), [Re­(PSiso)₂(<i>i</i>-Pr-Tiox)] (<b>Re2</b>), [Re­(PS2)₂(PyS)] (<b>Re3</b>), and [Re­(PSiso)₂(PyS)] (<b>Re4</b>), where PS2 = 2-(di­phenyl­phosphino)­ethane­thiolate and PSiso = 2-(di­isopropyl­phosphino)­ethane­thiolate, and the structural X-ray analysis of complex <b>Re3</b> were carried out. ^99mTc analogues of complexes <b>Re2</b> (^<b>99m</b><b>Tc2</b>) and <b>Re4</b> (^<b>99m</b><b>Tc4</b>) were obtained in high radiochemical yield following a simple one-pot procedure. The chemical identity of the radiolabeled compounds was confirmed by chromatographic comparison with the corresponding rhenium complexes and by dual radio/UV HPLC analysis combined with ESI­(+)-MS of ^99g/99mTc complexes prepared in carrier-added conditions. The two radiolabeled complexes were stable with regard to trans chelation with cysteine, glutathione, and ethylene­diamino­tetra­acetic acid and in rat and human sera. This study highlights the substitution-inert metal-fragment behavior of the [M­(PS)₂]⁺ framework, which reacts with suitable bidentate coligands to form stable hexacoordinated asymmetrical complexes. This feature makes it a promising platform on which to develop a new class of Re/Tc complexes that are potentially useful in radiopharmaceutical applications