Complex Formation of Silver(I) Ion with Some Aliphatic Diamines

Abstract

Abstract Complex formation of silver(I) ion with 1,3-propanediamine and 1,4-butanediamine has been studied poten-tiometrically at 25 °C in 3 mol dm−3 LiClO4 aqueous solution. Some additional experiments have been carried out in the system of silver-1,2-ethanediamine of large diamine/Ag ratios, the system having been examined in a previous work at small diamine/Ag ratios. Over the pH range of 6—10.4, the emf data obtained in the silver-diamine solutions could be explained in terms of the formation of the following complexes (L denotes the free diamine molecule): In a solution of low pH (pH=6—8), the AgHL2+ and AgH2L23+ complexes are formed. In an alkaline solution, the AgL+, Ag2L22+, and AgL2+ complexes are formed, and the relative amounts of the complexes depend on the concentrations of the metal and ligand (L) and also the ratio of these concentrations. The Ag(OH)L complex becomes a main species at the highest pH examined. In some cases the formation of the AgHL22+, Ag2HL23+, and Ag2L2+ complexes is suggested from the graphical or computer analysis of the data, but the formation constants of the complexes are rather uncertain. Over the whole pH range examined, the AgHL2+, AgH2L23+, AgL+, and Ag2L22+ complexes are predominant in all the systems.