Low Temperature Activation of Tellurium and Resource‐Efficient Synthesis of AuTe2 and Ag2Te in Ionic Liquids

Abstract

Abstract The low temperature syntheses of AuTe2 and Ag2Te starting from the elements were investigated in the ionic liquids (ILs) [BMIm]X and [P66614]Z ([BMIm]+=1‐butyl‐3‐methylimidazolium; X = Cl, [HSO4]−, [P66614]+ = trihexyltetradecylphosphonium; Z = Cl−, Br−, dicyanamide [DCA]−, bis(trifluoromethylsulfonyl)imide [NTf2]−, decanoate [dec]−, acetate [OAc]−, bis(2,4,4‐trimethylpentyl)phosphinate [BTMP]−). Powder X‐ray diffraction, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy revealed that [P66614]Cl is the most promising candidate for the single phase synthesis of AuTe2 at 200 °C. Ag2Te was obtained using the same ILs by reducing the temperature in the flask to 60 °C. Even at room temperature, quantitative yield was achieved by using either 2 mol % of [P66614]Cl in dichloromethane or a planetary ball mill. Diffusion experiments, 31P and 125Te‐NMR, and mass spectroscopy revealed one of the reaction mechanisms at 60 °C. Catalytic amounts of alkylphosphanes in commercial [P66614]Cl activate tellurium and form soluble phosphane tellurides, which react on the metal surface to solid telluride and the initial phosphane. In addition, a convenient method for the purification of [P66614]Cl was developed.

Keywords

• ionic liquid
• purification of ionic liquids
• silver telluride, tellurium
• 125Te-NMR