“…The stability of Tc(VI) and Tc(V) is remarkably different in nonaqueous solvents or in the presence of specific coordinating ligands, for which a variety of complexes and solid compounds are reported in the literature. − Indeed, gluconate complexes of Tc(V) are used as precursors of new Tc complexes by ligand exchange. ,, Tc(III) is stabilized in acidic reducing conditions, , with mixed Tc(III,IV) soluble species being reported in very acidic sulfate and chloride solutions. , Due to the relatively high electron density provided by the d 4 configuration of Tc(III), ligands with back donation capabilities are also reported to stabilize this oxidation state: carbonyl, thiourea, and aminopolycarboxylates (EDTA, NTA, etc. ), among others. ,, Rard and co-workers concluded that there is no experimental evidence for the existence of thermodynamically stable Tc(II) in aqueous solution . However, this elusive oxidation state in the aqueous phase can be stabilized in organic solvents in the presence of ligands with sulfur, halogen, and nitrogen donor atoms. ,− Several nitrosyl and thionitrosyl complexes of Tc(II) are also reported in the literature.…”