A Simple, Air Stable Single-Ion Source of Iron(I)

Molecular complexes of iron in the rare +1 oxidation state have been shown to be efficient catalysts for industrially relevant chemical transformations, typically associated with the increasingly unsustainable noble metals. Unlike many of these precious metals, iron does not have a suitable starting material in the reactive oxidation state and relies on the use of strong reducing agents (e.g., KC$_8$, RMgX) for access. Here, we present the synthesis, characterization, and reactivity of an air stable iron(I) arene complex, [Fe(durene)$_2$]$^+$ (durene = 1,2,4,5-tetramethylbenzene). Circumventing the use of reductants, we demonstrate that this general, single-source precursor can be used to modularly access a library of iron(I) compounds, all featuring well-studied donor ligands, including novel examples inaccessible by reduction. As a proof of concept, we further show that our single-ion source can access highly active catalysts in situ, showing future scope for iron(I) high throughput experimentation. [Fe(durene)$_2$]$^+$ represents the first stable iron(I) synthetic starting point.