Hexafluoridotechnetate(IV) Revisited

Abstract

Novel synthetic routes to hexafluoridotechnetate(IV) are reported, and for the first time the single-crystal X-ray structures of several M2[TcF6] salts (M = Na, K, Rb, Cs, NH4, and NMe4) were determined. The ammonium and the alkaline metal salts crystallize in the trigonal space group P3m, while the NMe4(+) salt belongs to the space group R3. [TcF6](2-) salts are widely stable in aqueous solution. In alkaline media, however, a slow hydrolysis is observed, and the first hydrolysis product, the dimeric, oxido-bridged complex [F5Tc-O-TcF5](4-), could be studied structurally.

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

“…The [TcF 6 ] 2À anion exhibits a slightly distorted octahedral geometry, with Tc-F bond lengths varying from 1.9266 (10) to 1.9487 (10) Å and an average Tc-F distance of 1.933 Å . This value is very similar to those observed in M 2 [TcF 6 ] (M = Rb and Cs) and slightly longer than those observed in A 2 [TcF 6 ] (A = Na, K, NH 4 , and NMe 4 ) (Balasekaran et al, 2013). The angles around the Tc atom are close to octahedral values ( Table 2).…”

“…Rb, and Cs) (Balasekaran et al, 2013). The electrochemical properties of (AsPh 4 ) 2 [TcF 6 ]Á2H 2 O were investigated by cyclic voltammetry in acetonitrile and compared with those of (n-Bu 4 N)[TcX 6 ] (X = Cl and Br) (Trop et al, 1979).…”

“…The first reported crystallographic information on a [TcF 6 ] 2À salt is a powder X-ray diffraction study of K 2 [TcF 6 ] (Schwochau & Herr, 1963), while other alkali metal salts of [TcF 6 ] 2À have been reported occasionally and do not contain any details of these compounds (Schwochau, 1964). The reinvestigation of the preparation, spectroscopic and solid-state structures of hexafluoridotechnetate(IV) was reported recently, however, its structural chemistry is limited to alkali metals, ammonium, and tetramethylammonium salts (Balasekaran et al, 2013). These Tc IV salts were obtained by metathesis reactions or by reduction of pertechnetate with sodium dithionate or zinc dust in the presence of HF (aq) .…”

Tetrafluoridonitridotechnetate(VI) – Reactions and Structures

“…With regard to our recent experience with the isolation of [TcF 6 ] 2– and [Tc(NO)F 5 ] 2– salts, where sometimes the selection of an appropriate counterion (or mixtures of such ions) played a crucial role, we started a re‐investigation of the behavior of the nitridofluorides of technetium(VI) in solution and isolated two of the products in crystalline form.…”

Tetraethylammonium Hexafluoro Uranate(IV), Hafnate(IV), and Cerate(IV) Salts: Preparation and Solid‐state Structure

“…In our study of group VII quadrivalent metal fluoride salts, we have investigated the preparation, spectroscopic properties, and solid‐states structures of A 2 M IV F 6 salts ( A = K, Rb, Cs; M = Tc and Re) . The Tc IV salts were obtained by metathesis reactions or by reduction of pertechnetate with sodium dithionate in the presence of HF aq ,[1a] whereas the Re IV salts were obtained by solid‐state melt reactions from [Re X 6 ] 2– ( X = Cl, Br) with NH 4 HF 2 or KHF 2 . [1b] Encouraged by our results on Tc and Re, we decided to explore the coordination and synthetic chemistry of other tetravalent metal fluoride, including lanthanides ( Ln ) and actinides ( An ).…”