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A novel propargyl-substituted thiocarbamoylbenzamidine has been synthesized. The compound acts as a tetradentate ligand and forms stable complexes with the {ReVO}3+ and {TcVO}3+ cores. 'Click' couplings of the resulting complexes with benzyl azide lead to prototype triazole derivatives, which were analyzed by NMR, IR, and mass spectrometry as well as by X-ray diffraction. A similar coupling procedure has been applied for an azido-modified angiotensin-II peptide, which gives the desired rhenium(V) bioconjucate with good yields. The ease of this coupling and the stability of the conjugate recommends such tetradentate thiocarbamoylbenzamidines also for clinically relevant bioconjugates with 99mTc.

N-[3-(Phenyltellanyl)propyl]picolinamide (HL1) or N-[N″,N″-methyl(phenyl)aminothiocarbonyl]-N′-[3-(phenyltellanyl)propyl]benzamidine (HL2) react with equivalent amounts of PtCl2 or PdCl2 with formation of neutral [MCl(L1-κN,N′,Te)] or [MCl(L2-κS,N,Te)] chelates. A corresponding reaction of HL2 with HgCl2 results in the formation of [HgCl2(HL2-κS,Te)]. Treatment of [PtCl(L1-N,N′,Te)] with elemental iodine results in the exclusive oxidation of the metal ion and the platinum(IV) complex [PtI3(L1-κN,N′,Te)] could be isolated in reasonable amounts. A decomposition of the tellurium-containing ligand and the formation of [PdI2(PhTeI)2] was observed during a similar procedure with the corresponding palladium complex. The bonding situation inside the latter compound was analyzed through density functional theory calculations.

Oxidorhenium(V) complexes with N,N-dialkyl-N′-benzoylselenoureas (HL) were prepared from reactions with (NBu4)[ReOCl4]. The formation of compounds such as [ReO(L-κO,Se)2(OMe)] or [{ReO(L-κO,Se)2}2O] suggests parallels with the established chemistry of corresponding benzoylthioureas, while the isolation of unusual species such as [ReO(L-κO,Se)2(L-κSe)], [{ReO(L-κO,Se)2}2Se3] and the formation of the respective diselenide suggest a more complicated reaction pathway with the unstable selenium compounds, and one in which degradation products of the ligands also plays a role.

Reactions of (NBu 4 )[ReOCl 4 ] with N-(N",N"-dialkylaminothiocarbonyl)-N'-(2-hydroxyphenyl)benzamidines (H 2 L 1 ) give complexes of the compositions [ReOCl(L 1 )] (1), cis-[ReO(L 1 )(OMe)] (2), or cis,cis-[{ReO(L 1 )} 2 O] (3) depending on the conditions applied. Compound 3 contains a bridging oxygen atom in the cis position to the terminal oxido ligands of both rhenium atoms. The analogous dimeric, sulfur-bridged compound [{ReO(L 1 )} 2 S] (4) was obtained by the reaction of 1 with Na 2 S.

Tricarbonylrhenium(I) and -technetium(I) halide (halide = Cl and Br) complexes of ligands derived from 4,5-diazafluoren-9-one (df) and 1,10-phenanthroline-5,6-dione (phen) derivatives of benzoic and 2-hydroxybenzoic acid hydrazides have been prepared. The complexes have been characterized by elemental analysis, MS, IR, 1 H NMR and absorption and emission UV/Vis spectroscopic methods. The metal centres (Re I and Tc I ) are coordinated through the nitrogen imine atoms and establish five-membered chelate rings, whereas the hydrazone groups stand uncoordinated. The 1 H NMR spectra suggest the same behaviour in solution on the basis of only marginal variations in the chemical shifts of the hydrazine protons.

Mixed-ligand complexes of technetium(V) or rhenium(V) containing tridentate N- ((dialkylamino)(thiocarbonyl))benzamidine (H2L1) and bidentate N,N-dialkyl-N'-benzoylthiourea (HL2) ligands were formed in high yields when (NBu4)(MOCl4) (M = Tc or Re) or (ReOCl3(PPh3)2) was treated with mixtures of the proligands. Other approaches for the synthesis of the products are reactions of (MOCl(L1)) complexes with HL2 or compounds of the composition (ReOCl2(PPh3)(L2)) with H 2L1. The resulting air-stable (MO(L1)(L 2)) complexes possess potential for the development of metal-based radiopharmaceuticals. (TcO(L1)(L2)) complexes are readily reduced by PPh3 with formation of (Tc(L1)(L 2 )(PPh3)). The resulting TcIII complexes undergo two almost-reversible oxidation steps corresponding to one-electron transfer processes. ?? 2009 Wiley-VCH Verlag GmbH & Co, KGaA. Author Keywords: Rhenium; S,N,O ligands; S,O ligands; Structure elucidation; Synthetic methods; Technetium

Pyridine- and pyrazine-2-carboxamide thiosemicarbazones (HAm4DH and HAmpz4DH) or their N4,N4-dimethyl derivatives (HAm4DM and HAmpz4DM) react with chloro[2-(dimethylaminomethyl)phenyl-C1]mercury (II), [Hg(damp)Cl], to give the tetrahedral [Hg(TSC)2] complexes [TSC = Am4DH (1), Am4DM (2), Ampz4DH (3) or Ampz4DM (4)]. Spectroscopic studies and a X-ray structural analysis show that the potentially tridentate thiosemicarbazones adopt S,N coordination modes, with each deprotonated thiosemicarbazone binding to the HgII centre through the azomethine nitrogen and the thiolate sulfur atoms, whereas the heterocyclic nitrogen atoms are free of coordination. Intra- and intermolecular hydrogen bonding in all complexes and specific C-H⋯π interactions with the chelate or pyridyl rings of the complexes 1 and 2 were found in the crystal structures. Furthermore, [Hg(damp)Cl] undergoes symmetrisation to give the symmetric unit [Hg(Hdamp)2]2+ in which the Hdamp is protonated at the nitrogen. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.