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A novel mixed ligand hexacoordinated rhenium(III) complex of the general formula ReIII[P][NN][S][SO] has been synthesized by reacting ReVOCl3(PPh3)2 with 2,2′-bipyridine (NN), p-thiocresol (S) and N-acetyl-l-cysteine (SO) in a 1:1:1:1 ratio in methanol. During the reaction, the central rhenium atom undergoes reduction from Re(V) to Re(III). The complex was isolated as red crystals and characterized by elemental analysis, IR and NMR spectroscopies. X-ray crystallographic studies showed that the coordination geometry around rhenium is distorted octahedral. The equatorial plane is defined by the two nitrogen atoms of 2,2′-bipyridine, the sulfur of N-acetyl-l-cysteine and the sulfur of the aromatic thiol, while the phosphorous and the carboxylate oxygen of N-acetyl-l-cysteine occupy the apical positions. [Copyright &y& Elsevier]

A series of 99mTcO[SN(R)S][S] complexes carrying the 1-(2-methoxyphenyl)piperazine moiety on the tridentate ligand [SN(R)S] was synthesized. For structural characterization and for in vitro binding assays the analogous oxorhenium complexes were prepared. As demonstrated by appropriate competition binding tests in rat hippocampal preparations, all oxorhenium analogues showed affinity for the 5-HT1A receptor binding sites with IC50 values at the nanomolar range (IC50= 5.8–103 nM). All 99mTcO[SN(R)S]/[S] complexes showed significant brain uptake in rats at 2 min p.i. (0.24–1.31% ID). However, a clear correlation between distribution of radioactivity in the brain and distribution of 5-HT1A receptors could not be established. [Copyright &y& Elsevier]

The synthesis, characterization and biological evaluation of two novel 3 + 1 mixed ligand 99mTc-complexes, bearing the 1-(2-methoxyphenylpiperazine) moiety, a fragment of the true 5-HT1A antagonist WAY 100635, is reported. Complexes at tracer level 99mTcO[(CH3CH2)2NCH2CH2N(CH2CH2S)2][o-CH3OC6H4N(CH2CH2)2NCH2CH2S], 99mTc-1, and 99mTcO[((CH3)2CH)2NCH2CH2N(CH2CH2S)2][o-CH3OC6H4N (CH2CH2)2NCH2CH2S], 99mTc-2, were prepared using 99mTc-glucoheptonate as precursor. For structural characterization, the analogous oxorhenium complexes, Re-1 and Re-2, were prepared by ligand exchange reaction using ReOCl3(PPh3)2 as precursor, and characterized by elemental analysis and spectroscopic methods. Complex Re-1 was further characterized by crystallographic analysis. Labeling was performed with high yield (>85%) and radiochemical purity (>90%) using very low ligand concentration. The structure of 99mTc complexes was established by comparative HPLC using the well-characterized oxorhenium analogues as references. In vitro binding assays demonstrated the affinity of these complexes for 5-HT1A receptors (IC50 : 67 and 45 nM for Re-1 and Re-2 respectively). Biological studies in mice showed the ability of 99mTc-1 and 99mTc-2 complexes to cross the intact blood-brain barrier (1.4 and 0.9% dose/g, respectively at 1 min post-inj.). The distribution of these complexes in various regions in rat brain is inhomogeneous. The highest ratio between areas reach and poor in 5-HT1A receptors was calculated for complex Tc-1 at 60 min p.i. (hippocampus/cerebellum = 1.7). [Copyright &y& Elsevier]

Presents a synthesis and characterization of mixed-ligand oxerhenium complexes with the SNN type ligand. Synthesis; X-ray studies of compounds; NMR studies of complexes.

The synthesis, radiochemistry and biodistribution in mice of 99mTcO{[(CH3CH2)2NCH2CH2-N(CH2CH2S)2] ( p-SPh-COOCH2CH3)}, I, are reported herein. Complex I forms by binding of (CH3CH2)2NCH2CH2N(CH2CH2SH)2 and p-HSPhCOOCH2CH3 ligands to reduced 99mTc using glucoheptonate (GH) as transfer ligand. Corroboration of structure with an authentic 99gTc sample is achieved by reverse phase high pressure liquid chromatography (RP-HPLC) adopting parallel radiometric and photometric detection modes. By incubation at 37°C with glutathione (GSH) in aqueous medium I tranforms to an hydrophilic compound, as shown by HPLC. Tissue distribution experiments reveal high uptake and retention of I in mice brain. [ABSTRACT FROM AUTHOR]

Studies a donor atom system for the synthesis of neutral oxotechnetium(V) mixed-ligand complexes. Preparation of the mixed-ligand complexes; Characterization of the infrared spectra of the complexes; Summary of crystal, intensity collection and refinement data; Bond distances and angles; List of chemical shifts for the complexes.