Monomer, μ-Oxo Dimer, Di(μ-Oxo) Dimer Interconversion of Nitridotechnetium(VI) Complexes in Solution

Abstract

Nitrido / Technetium(VI) / Monomer / fi-Oxo dimer / Di(ii-oxo) dimer / Monomer and dimer interconversions SummaryThe interconversion of monomeric and ^-oxo and di(/i-oxo) dimeric nitridotechnetium(VI) species in Solution has been studied by ESR and UV-Vis spectrophotometry. High acidity and the presence of coordinating anions favour the monomeric form. In very weakly coordinating acids the n-oxo and di(ß-oxo) aquanitrido cations have been identified. (AsPh4)2[{TcNX2}2(A'-0)2] (X = Cl, Br) have been prepared and the chloro complex shown to be a useful starting material for the preparation of di{/i-oxo) dimers by substitution.

Fluoridonitrosyl Complexes of Technetium(I) and Technetium(II). Synthesis, Characterization, Reactions, and DFT Calculations

“…This implies that in aqueous solution a species with Tc–Tc interactions is formed. Similar results have been reported for nitridotechnetium(VI) compounds, where treatment of Cs 2 [TcNCl 5 ] or (NBu 4 )­[TcNCl 4 ] with water gives [{TcNCl 2 } 2 (μ-O) 2 ] 2– , a bis­(μ-oxido)­technetium­(VI) compound, , which also can be reconverted into the mononuclear [TcNCl 5 ] 2– upon dissolution in concentrated HCl. All attempts to isolate the assumed [{Tc­(NO)­F 2 } 2 (μ-O) 2 ] 2– with large cations such as NBu 4 + or AsPh 4 + from aqueous solution failed up to now, while the blue crystals of K 2 [Tc­(NO)­F 5 ]·H 2 O were reformed after complete evaporation of the water.…”

Anion⋯anion self-assembly under the control of σ- and π-hole bonds

“…Bond paths and bond CPs have been found for these interactions and NCIPlot analyses revealed extended green/blue surfaces. 25,129 Tetrachloro-nitrido-technetate anions adopt a square pyramidal geometry and afford matere bonded infinite chains 129,138 via the approach of the nitrogen to the s-hole at technetium opposite to the TcRN bond (Fig. 12).…”

A Combined Study of Tc Redox Speciation in Complex Aqueous Systems: Wet-Chemistry, Tc K-/L3-Edge X-ray Absorption Fine Structure, and Ab Initio Calculations

“…The importance of Tc­(IV) sulfide compounds (mostly as TcS 2 and Tc 2 S 7 ) is reported in the fields of medicine, nuclear waste disposal, or environmental applications. − In aqueous systems, the formation of Tc­(VI) and Tc­(V) is described in a number of electrochemical/polarography studies. − Because of their involvement in fast disproportionation reactions, both oxidation states are considered unstable in aqueous equilibrium systems . 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 .…”