Nitrite Activation to Nitric Oxide via One-fold Protonation of Iron(II)‑<i>O</i>,<i>O</i>‑nitrito Complex: Relevance to the Nitrite Reductase Activity of Deoxyhemoglobin and Deoxyhemerythrin

The reversible transformations [(Bim)3Fe­(κ2-O2N)]­[BF4] (3) ⇌ [(Bim)3Fe­(NO)­(κ1-ONO)]­[BF4]2 (4) were demonstrated and characterized. Transformation of O,O-nitrito-containing complex 3 into [(Bim)3Fe­(μ-O)­(μ-OAc)­Fe­(Bim)3]3+ (5) along with the release of NO and H2O triggered by 1 equiv of AcOH implicates that nitrite-to-nitric oxide conversion occurs, in contrast to two protons needed to trigger nitrite reduction producing NO observed in the protonation of [FeII-nitro] complexes.