Reactions of the nitrosodisulfonate anion radical with s2 reducing centers

Abstract

The nitrosodisulfonate anion radical, ˙NO(SO₃)₂²⁻, a single electron oxidant, reacts rapidly with the 2e⁻ metal-based reductants, Sn(II) and Ge(II) (k = 10⁴–10⁵ M⁻¹ s⁻¹), less rapidly with sulfite (k = 0.24 M⁻¹ s⁻¹) and very slowly (10⁻³–10⁻² M⁻¹ s⁻¹) with the nonmetal-based donors, H₂AsO₃⁻, Sb^III(tartrate), hyponitrite, and hypophosphite. Reductions yield the product HON(SO₃)₂²⁻. Kinetic profiles exhibit no irregularities attributable to generation or loss of a transient on a time scale comparable to the principal conversion, indicating that rates are determined by the original 1e⁻ transfer and that the “follow-up” step is rapid. Reductions by sulfite (pH 4.2–8.6) are retarded by partial conversion to HSO₃⁻, whereas those by Sn(II) and Ge(II) (in 0.1–1.0 M H⁺) are accelerated by H⁺. Rates for Sn(II) are markedly enhanced by chloride, suggesting stabilization of intervening chloro-ligated Sn(III).