title: Synthesis and characterization of novel oxotechnetium (99Tc and 99mTc) and oxorhenium complexes from the 2,2'-bipyridine (NN)/thiol (S) mixed-ligand system.
abstract: The synthesis and characterization of oxotechnetium and oxorhenium mixed-ligand complexes of the general formula MO[NN][S](3) (M = (99)Tc and Re), where NN represents the bidentate ligand 2,2'-bipyridine and S represents a monodentate thiophenol, is reported. The complexes were prepared by ligand exchange reactions using (99)Tc-gluconate and ReOCl(3)(PPh(3))(2) as precursors for the oxotechnetium and oxorhenium complexes, respectively. Compound 1 (M = (99)Tc, S = 4-methylthiophenol) crystallizes in the monoclinic space group P2(1)/a, a = 23.12(1) A, b = 14.349(6) A, c = 8.801(4) A, beta = 94.81(2) degrees, V = 2918(2) A(3), Z = 4. Compound 3 (M = Re, S = 4-methylthiophenol) crystallizes in the monoclinic space group P2(1)/a, a = 23.018(9) A, b = 14.421(5) A, c = 8.775(3) A, beta = 94.78(1) degrees, V = 2903(2) A(3), Z = 4. Compound 4 (M = Re, S = 4-methoxythiophenol) crystallizes in the orthorhombic space group Pbca, a = 16.32(1) A, b = 24.55(2) A, c = 16.94(1) A, V = 6788(9) A(3), Z = 8. In all cases, the coordination geometry around the metal is distorted octahedral with the equatorial plane being defined by the three sulfur atoms of the thiophenols and one nitrogen atom of 2,2'-bipyridine, while the apical positions are occupied by the second nitrogen atom of 2,2'-bipyridine and the oxygen of the M=O core. The complexes are stable, neutral, and lipophilic. Complete (1)H and (13)C NMR assignments are reported for all complexes. The analogous oxotechnetium complexes have been also synthesized at tracer level ((99m)Tc) by mixing the 2,2'-bipyridine and the corresponding thiol with Na(99m)TcO(4) generator eluate using NaBH(4) as reducing agent. Their structure was established by chromatographic comparison with authentic oxotechnetium and oxorhenium complexes using high performance liquid chromatography techniques.
authors.affiliation: Institute of Radioisotopes-Radiodiagnostic Products, National Centre for Scientific Research Demokritos, 15310 Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Papachristou
authors.forename: Ioannis C
authors.initials: IC
authors.lastname: Pirmettis
authors.forename: Charalambos
authors.initials: C
authors.lastname: Tsoukalas
authors.forename: Dionyssia
authors.initials: D
authors.lastname: Papagiannopoulou
authors.forename: Catherine
authors.initials: C
authors.lastname: Raptopoulou
authors.forename: Aris
authors.initials: A
authors.lastname: Terzis
authors.forename: Chariklia I
authors.initials: CI
authors.lastname: Stassinopoulou
authors.forename: Efstratios
authors.initials: E
authors.lastname: Chiotellis
authors.forename: Maria
authors.initials: M
authors.lastname: Pelecanou
authors.forename: Minas
authors.initials: M
authors.lastname: Papadopoulos
mesh_terms: D015082:2,2'-Dipyridyl; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents; D003224:Congo Red; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D012211:Rhenium / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013667:Technetium / Q000737:chemistry*; D017556:Technetium Compounds / Q000138:chemical synthesis*
chemical_list: D004396:Coloring Agents; D007202:Indicators and Reagents; D008024:Ligands; D019275:Radiopharmaceuticals; D013438:Sulfhydryl Compounds; D017556:Technetium Compounds; D003224:Congo Red; D015082:2,2'-Dipyridyl; D012211:Rhenium; D013667:Technetium