text: Iron is a popular research target for many catalytic processes, owing largely to its low cost and low toxicity relative to other transition metals.  Asymmetric hydrogenation methods using iron have been realized, although in terms of rates and selectivity, they are inferior to catalysts based on precious metals.  In some cases, structurally ill-defined nanoparticles have proven to be the active species in situ and the modest selectivity observed may result from their uncontrolled geometries.