Coexistence of Tellurium Cations and Anions in Phosphonium‐Based Ionic Liquids

Abstract

Elemental tellurium readily dissolves in ionic liquids (ILs) based on tetraalkylphosphonium cations even at temperatures below 100 °C. In the case of ILs with acetate, decanoate, or dicyanamide anions, dark red to purple colored solutions form. A study combining NMR, UV‐Vis and Raman spectroscopy revealed the formation of tellurium anions (Ten)2− with chain lengths up to at least n=5, which are in dynamic equilibrium with each other. Since external influences could be excluded and no evidence of an ionic liquid reaction was found, disproportionation of the tellurium is the only possible dissolution mechanism. Although the spectroscopic detection of tellurium cations in these solutions is difficult, the coexistence of tellurium cations, such as (Te4)2+ and (Te6)4+, and tellurium anions could be proven by cyclic voltammetry and electrodeposition experiments. DFT calculations indicate that electrostatic interactions with the ions of the ILs are sufficient to stabilize both types of tellurium ions in solution.

Exploration of metal sulfide syntheses and the dissolution process of antimony sulfide in phosphonium-based ionic liquids

“…A parallel observation was recently made for tellurium in the same phosphonium-based ILs. 57,58 With stirring and heating, the acetate IL darkened completely to a dark red to brownish solution at a molar ratio of Cu : S = 1 : 1, and a dark green solution was formed for 2 : 1.…”

Low‐Temperature Synthesis of NiSb2, Cu2Sb, InSb and Sb2Te3 Starting from the Elements

“…Since we did not observe any redox reactions other than the formation of Cu 2 Sb, there are only two obvious mechanisms for the activation of antimony. In one case, antimony could disproportionate, similar to what was observed for tellurium [22d] and selenium [29] . Polyatomic antimony ions such as Sb 8 2+[30] and Sb 7 3− , [31] would be stabilized by the ionic medium and additional nucleophiles.…”

“…The ILs (from IoLiTec) [P 66614 ][DCA]>95 %, [P 66614 ][NTf 2 ] 99 %, and [BMIm]Cl 99 %, [BDMIm]Cl 99 %, [BMIm][OAc]>98 %, [P 66614 ]Cl>95 % were dried at 110 °C for 16 h at about 10 −3 mbar and stored under inert conditions inside a glovebox. [P 66614 ][OAc] was synthesized by anion metathesis from the chloride IL using K[OAc] according to a literature procedure [22c,d,36] …”

Processing Gray Selenium in Phosphonium-Based Ionic Liquids

“…At temperatures of about 200 °C, the phosphonium cation reacts with elemental selenium or tellurium to form organophosphorus­(V) chalcogenides R 3 PCh (Ch = Se, Te). , Furthermore, trialkylphosphanes (PR 3 ) are common impurities in commercial phosphonium-based ILs that also react with elemental chalcogens to form R 3 PCh. ,,, In our experiments, the dissolution of selenium was carried out at temperatures well below 100 °C to prevent such reactions of the ILs. Before selenium dissolution, a ratio between 31 P NMR signal intensities of [P 66614 ] + and PR 3 of 1:0.004 was determined.…”