Spectrophotometric investigation of complex formation between HMPAO and palladium(II) ions

Abstract

A system containing palladium(II) ions and dioxime HMPAO (H 2 L; L 2 = 4,8-diaza-3,6,6,9-tetramethylundecane-2, 10-dione dioximate ion) was investigated within a pH range of 2.0 to 7.5 (1 = 0.5 mol dm 3 ) using spectrophotometric measurements. Experimental data proved the formation of two different complex types: one with excessive Pd(II) ions (λ max = 370 nm) and the other with excessive HMPAO, λ max = 240 nm, HMPAO to Pd(II) ratio 1:1, and a relative stability constant log β' = 4.64 ± 0.05, at 293 K. The probable structure of the complex [Pd(HL)] + in solution is also suggested.