Synthesis and electrochemistry of (.mu.-oxo)technetium complexes with bipyridine and halide ligands. Crystal structures of (.mu.-O)[X(bpy)2Tc]2X2.cntdot.bpy ( X = Cl, Br) and (.mu.-O)[Cl(phen)2Tc]2Cl2

Photochemical behaviour of Tc2OCl10 4– and TcnOy 4n–2y+ in chloride media

The stabilities of the technetium polymers Tc2OCl10 4− and TcnOy 4n−2y+ have been studied under light irradiation in 3 M chloride media with a pH range from 0 to 1.3. It has been shown that under irradiation, Tc2OCl10 4− is not stable and undergoes dissociation to TcCl5(H2O)- at pH = 0 and pH = 0.3. At pH = 1, irradiation of Tc2OCl10 4− leads to a stationary state involving TcCl5(H2O)- and Tc2OCl10 4−. At pH = 1.3, TcnOy 4n−2 y+ remains stable under irradiation. Under light irradiation, the predominance diagram of Tc(IV) species obtained from Tc2OCl10 4− aquation in a pH range from 0 to 1 is drawn.

The chemical behaviour of Tc2OCl10 4− and the influence of the light on the condensation of Tc(IV) and solubility of TcO2· x H2O are discussed.

Synthesis and Structure of Novel Sugar-Substituted Bipyridine Complexes of Rhenium and 99m-Technetium

Novel ligands have been obtained from the reaction of 4,4'-dibromomethyl-2,2'-bipyridine with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylthiol, 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosylthiol or 2,3,4,6-tetra-O-acetyl-alpha-D-thioacetylmannopyranoside in which the sugar residues are thioglycosidically linked to the bipyridine in the 4,4'-position. Cleavage of the acetyl groups affords hydrophilic symmetric ligands with free hydroxyl groups. Reaction of the new glycoconjugated ligands (L) with [Re(CO)(5)Cl] yields fluorescent complexes of general formula [Re(L)(CO)(3)Cl], which were characterised by mass spectrometry, elemental analysis and (1)H and (13)C NMR, IR, UV/Vis and fluorescence spectroscopy. These complexes exhibit excellent solubility and stability in organic solvents or water, depending on the residues of the sugar. One complex, namely tricarbonyl-4,4'-bis[(2,3,4,6-tetra-O-acetyl-beta-D-glycopyranosyl)thiomethyl]-2,2'-bipyridinerheniumtricarbonylo chloride, has been characterised by X-ray crystallography. A non-symmetric structure of the complexes could be assigned. Radiolabelling of the unprotected ligands with [(99m)Tc(H(2)O)(3)(CO)(3)](+) affords the corresponding water-soluble technetium complexes (in quantitative yields), which were characterised by their HPLC radiation traces. The formed complexes are stable for several hours in the presence of histidine but show partial ligand-exchange after one day.

Technetium Tetrachloride as A Precursor for Small Technetium(IV) Complexes

Polymeric technetium tetrachloride reacts with monodentate donor ligands such as THF, acetonitrile, DMSO, thioxane (1-oxa-4-thiacyclohexane), PMe2Ph, PPh3, OPPh3, or OH2 via cleavage of the polymeric network and the formation of [TcCl4(L)2] complexes. The configuration of the products is dependent on the donor atoms such that trans coordination is established with "soft" donor atoms such as sulfur or phosphorus, while cis-[TcCl4(L)2] complexes are formed with the "harder" donors oxygen or nitrogen. The ambivalent thioxane binds to technetium via the sulfur atom. The trans products are air stable and resistant to hydrolysis. The cis complexes, however, undergo stepwise hydrolysis, during which complexes of the composition [Cl3(L)2TcOTc(L)2Cl3] (L = CH3CN, DMSO, or OH2) are formed. They are the first representatives of a new class of technetium(IV) complexes with a bridging oxo ligand. The Tc-O bond lengths in these bridges are between 1.803(1) and 1.823(2) A.

[TcCl4(H2O)2] and [Cl3(H2O)2TcOTc(H2O)2Cl3]– two molecular intermediates of the hydrolysis of technetium(iv)

Two molecular intermediates of the hydrolysis of technetium tetrachloride, cis-[TcCl4(H2O)2] and [Cl3(H2O)2TcOTc(H2O)2Cl3], were isolated and structurally characterised, suggesting that the hydrolytic degradation of technetium(IV) compounds occurs stepwise with the polymeric 'TcO2...nH2O' as a less defined final product.