Kinetics of aquation of the complex tris[3-(2-pyridyl)-5,6-bis(4-phenylsulphonato)-1,2,4-triazine]iron(II) and its reactions with hydroxide, cyanide, and peroxodisulphate ions

Abstract

The kinetics of the reactions of the complex tris[3-(2-pyridyl)-5,6-bis(4-Phenylsulphonato)-1,2,4-triazine]iron(II) in acid soloution, and with hydroxide, cynide, and peroxodisulphate ions, and hydrogen peroxide, have been investigated. The dependence of the observed rate constants on reagent concentration has been established for the reactions in acid, and with hydroxide and peroxodisulphate ions, at 35·0 ° C. For the reaction with cyanide ions, the rate law has been established and, from measured rate constants over a range of cyanide-ion concentrations and over the temperature range 25·3–44·1 °C, activation parameters both for cyanide-ion attack and for complex dissociation have been estimated. The variation of the rate of cyanide-ion attack with solvent composition has been determined for ethanol–water mixtures containg up to 30% ethanol. Patterns of reactivity for this complex are compared with those previously established for other low-spin iron(II) chelate complexes.