Bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate: preparation, structure and spectroscopic analysis

Abstract

Reports of quadrivalent transition-metal fluoride salts containing bulky organic cations are limited. In this context, we prepared the bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate salt, (C24H20As)2[TcF6]·2H2O, by a cation metathesis reaction of (NH4)2[TcF6] in water. This is the first report of an arsonium salt of the hexafluoridotechnetate(IV) dianion. (AsPh4)2[TcF6]·2H2O crystallizes in the triclinic space group P\overline{1}. The [TcF6]2− anion adopts a slightly distorted octahedral geometry with an average Tc—F bond length of 1.933 Å. The cyclic voltammogram of (AsPh4)2[TcF6]·2H2O in CH3CN shows a one-electron reversible oxidation wave at 1.496 V.

Influence of the organic cation on the formation of hexahalotechnetates: X-ray, thermal and comparative analyses of non-covalent interactions

“…and F) with organic cations and electrically neutral molecules were found. [20][21][22][23][24][25][26][27][28][29][30][31] Only structures with refined hydrogen atoms and without disordering are suitable for the analysis of interactions. Only the following compounds were left for analysis: hexakis(N,N-dimethylformamide)-aluminium chloride hexachlorotechnetate N,N-dimethylformamide solvate (DOSREK), 47 bis(trichloro-tris (dimethylsulfoxide)-technetium(IV)) hexachloro-technetate(IV) (JEPQOL), 48 bis(triphenylphosphonium) hexachloro-technetium(IV) (KAXQUW), 49 bis(1,1-dimethyl-3-oxobutyl-tris(4methylphenyl)phosphonium) hexachloro-technetium(IV) (LALHAH), 50 and tetramethylammonium hexafluorotechnetate (IV) (XUNPAZ).…”

“…However, the Cambridge Bank of Crystal Structures 18,19 has only about 10 known compounds containing the Tc(Hal) 6 fragment with organic cations. [20][21][22][23][24][25][26][27][28][29][30][31] At the same time, for the closest chemical analogue of technetium, Re(IV), the extensive chemistry of hexahalotechnetates has about 110 compounds up to 2023. 32 Technetium halides may be of particular interest in the context of pyrochemical and extraction processing of spent fuel in melts and salt solutions, 33 also as the main form of technetium in the processing of molten salt reactor fuel.…”

“…However, the Cambridge Bank of Crystal Structures 18,19 has only about 10 known compounds containing the Tc(Hal) 6 fragment with organic cations. 20–31 At the same time, for the closest chemical analogue of technetium, Re( iv ), the extensive chemistry of hexahalotechnetates has about 110 compounds up to 2023. 32…”