Solubility, complex formation, and redox reactions in the Tl 2O3-HCN/CN--H2O system. Crystal structures of the cyano compounds Tl(CN)3·H2O, Na[Tl(CN)4]·3H2O, K[Tl(CN)4], and TlITlIII(CN)4 and of TlI2C2O
2005 (English)In: Inorganic Chemistry, ISSN 0020-1669, Vol. 44, no 7, 2347-2357 p.Article in journal (Refereed) Published
Thallium(III) oxide can be dissolved in water in the presence of strongly complexing cyanide ions. TlIII is leached from its oxide both by aqueous solutions of hydrogen cyanide and by alkali-metal cyanides. The dominating cyano complex of thallium(III) obtained by dissolution of Tl 2O3 in HCN is [Tl(CN)3(Bq)] as shown by 205Tl NMR. The Tl(CN)3 species has been selectively extracted into diethyl ether from aqueous solution with the ratio CN -/TlIII = = 3. When aqueous solutions of the MCN (M = Na+, K+) salts are used to dissolve thallium(III) oxide, the equilibrium in liquid phase is fully shifted to the [Tl(CN) 4]- complex. The Tl(CN)3 and Tl(CN) 4- species have for the first time been synthesized in the solid state as Tl(CN)3·H2O (1), M[Tl(CN) 4] (M = Tl (2) and K (3)), and Na[Tl(CN)4]·3H 2O (4) salts, and their structures have been determined by single-crystal X-ray diffraction. In the crystal structure of 1, the thallium(III) ion has a trigonal bipyramidal coordination with three cyanide ions in the equatorial plane, while an oxygen atom of the water molecule and a nitrogen atom from a cyanide ligand, attached to a neighboring thallium complex, form a linear O-Tl-N fragment. In the three compounds of the tetracyano-thallium(III) complex, 2-4, the [Tl(CN)4]- unit has a distorted tetrahedral geometry. Along with the acidic leaching (enhanced by TlIII-CN- complex formation), an effective reductive dissolution of the thallium(III) oxide can also take place in the Tl 2O3-HCN-H2O system yielding thallium(I), while hydrogen cyanide is oxidized to cyanogen. The latter is hydrolyzed in aqueous solution giving rise to a number of products including (CONH2) 2, NCO-, and NH4+ detected by 14N NMR. The crystalline compounds, TlI[Tl III(CN)4], TlI2C2O 4, and (CONH2)2, have been obtained as products of the redox reactions in the system. © 2005 American Chemical Society.
Place, publisher, year, edition, pages
2005. Vol. 44, no 7, 2347-2357 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-45469DOI: 10.1021/ic0485918OAI: oai:DiVA.org:liu-45469DiVA: diva2:266365