A new approach to the equilibrium study of iron(III) thiocyanates which accounts for the kinetic instability of the complexes particularly observable under high thiocyanate concentrations

作者：de Berg Kevin^*; Maeder Marcel; Clifford Sarah

来源：Inorganica Chimica Acta, 2016, 445: 155-159.

DOI：10.1016/j.ica.2016.02.052

• Iron thiocyanates
• Kinetic instability
• Initial spectrum
• Stability constants

The kinetic instability of iron(III) thiocyanate complexes in aqueous solution, evidenced by the loss of solution colour with time, has made it difficult to determine reliable equilibrium data. A technique, which measures the absorbance of these solutions as a function of time within milliseconds of mixing Fe3+ with SCN and which extrapolates to an initial spectrum at time zero, has been designed to overcome these difficulties and is described in this paper. Two complexes, Fe(SCN)(2)(+) and Fe(SCN)(2)(+), have been identified upon analysing the absorbance data for thiocyanate concentrations up to 0.25 M at 25 degrees C and an ionic strength of 0.5 M. Equilibrium constants, K-1 = (98 +/- 1) = M-1 and K-2 = (7 +/- 1) = M-1 have been determined and comparisons made with the literature.

• 出版日期2016-4-24