Raman spectra of copper(I), silver(I) and gold(I) cyanides in aqueous solutions of sodium thiosulphate

✍ Scribed by Mahmoud A. El-Hinnawi; Lyle Peter; B. Meyer

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 705 KB
• Volume: 16
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.1250160410

✦ Synopsis

Systems of copper(I), silver(1) and gold(1) cyanides dissolved in aqueous solutions of sodium thiosulphate in different molar ratios have been studied by Raman Spectroscopy. CuCN dissolves completely in aqueous thiosulphate solution in a 1:3 CuCN to S,03'ratio, forming only mixed cyanothiosulphate species. No evidence was found for the formation of Cu (CN),-, Cu(CN);-or Cu(CN)2-. The mixed cyano copper complex was isolated as a white solid insoluble in water and most other solvents. The solid probably consists of a polymeric structure with bridging cyanide and thiosulphate. AgCN dissolves completely in aqueous thiosulphate solution in a 1 : I AgCN to S2032ratio, resulting in the formation of Ag(CN)2-and Ag(S20&-species. As the concentration of thiosulphate increases Ag(CN)2(Sz03)3-and Ag(CN)z(S,0,)25-are formed. There is strong evidence for the existence of bridging silver thiosulphate complex in solutions of low SzO;concentration. AuCN dissolves completely in aqueous thiosulphate solution in a 1 :2 AuCN to SZO3'ratio, forming Au(CN)~-, Au(CN) (S2O3)'and Au(S,O,);-.

No evidence was found for the formation of species of higher coordination number on increasing the concentration of S20J2--, which indicates that the linear two-coordinate gold complexes are the most stable.