Chemical properties of the bis-(2,3,5,6-tetrakis(2'-pyridyl) pyrazine)-iron(II) complex

Abstract

2,3,5,6-Tetrakis(2'-pyridyl)pyrazine forms an iron(II) complex containing 2 moles of ligand for each mole of iron. In aqueous solution, the wavelength of maximum absorbance shifts from 575 nm to 590 nm when the complex solution is treated with strong acid. Both the protonated and non-protonated forms of the complex obey Beer's law over the range 8.95·10 -6-5.37·10 -5 M, the molar absorptivities of the protonated and non-protonated complexes being 16,700 and 19,210 respectively. The overall stability constant of the iron complex was found to be 8.5 ± 0.3. There are 3 protons per molecule in the protonated form.