The nature of Mn(II) complexes in concentrated aqueous ammonium oxalate solutions

✍ Scribed by E. Mielniczek-Brzóska

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 392 KB
• Volume: 45
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.201000377

✦ Synopsis

Abstract

The paper presents an analysis of the results of spectroscopic studies obtained in the ultraviolet range UV for unsaturated ammonium oxalate solutions containing Mn(II) impurity c~i~. The aim is to follow manganese oxalate formation processes at different ammonium oxalate concentrations c and Mn(II) impurity c~i~ and also to establish how concentrations of particular species change with a change of ratio (c~i~ /c). Spectroscopic analysis is discussed from the standpoint of speciation of these complexes in the abovementioned solutions. The coordination of C~2~O~4~^2–^ ligand with Mn(H~2~O)~6~^2+^ aquacomplex in the range ‐2 < ln(c~i~/c) < 1.5 leads to the formation of Mn(C~2~O~4~) and Mn(C~2~O~4~)~2~^2–^ complexes, but the coordination of the C~2~O~4~^2–^ ligand with Mn(C~2~O~4~)~2~^2–^ complex in the concentration ratio range ‐5 < ln(c~i~/c) < ‐2 results in the formation of predominantly Mn(C~2~O~4~)~3~^4–^ complex. The effect of successive coordination of the C~2~O~4~^2–^ ligand is well‐defined in the ultraviolet spectral region. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)