Iron catalysis of the reduction of oxime-bound nickel(IV) by hydroxylamine
Abstract
The nickel(IV) complex of the dianion of 2,6-diacetylpyridine dioxime was reduced very slowly by NH3OH+ at pH 1–3, but this reduction is catalysed dramatically by dissolved iron, with FeII being the active reductant. With NH3OH+ in excess, the products of the catalysed reaction are N2 and NiII. Non-exponential kinetic profiles for this reaction are consistent with a sequence in which FeII is generated by le– reduction of FeIII by NH2OH, after which FeII reduces NiIV to NiIIIvia competing protonated and non-protonated paths. Subsequent reduction of NiIII is taken to be rapid. Rate constants and equilibrium quotients calculated from 15 runs are in accord with literature values.