Electron spin resonance studies of γ-irradiated potassium hexacyanoferrate(II) in various host lattices

Abstract

Four major Fe^I species were detected, one exhibiting hyperfine coupling to one ¹⁴N nucleus (N₁), one with coupling to two equivalent ¹⁴N nuclei (N₂), one with coupling to one ¹⁴N nucleus and one halide nucleus (N₁Hal₁) and one with coupling to two equivalent halide nuclei (Hal₂). The N₁ species is thought to be Fe(CN)₄CN′H₂O^4–, formed from Fe(CN)₄H₂O^3– impurity ions, in which the CN' ligand is slightly bent off the Fe–CN axis. The N₂ species has two trans-cyanide ligands comparably bent off the axis. The halide complexes are then Fe(CN)_4^– CN′Hal^5– and Fe(CN)₄(Hal)₂^5– ions respectively, with the halide ligands or halide and bent cyanide ligands in a trans-configuration.

In one case, a species exhibited hyperfine coupling to one ¹⁴N nucleus and one proton. This is thought to be an Fe^I complex containing the Fe–CNH unit.