Hydrogen bonding (H-bonding) interactions within active sites are known to facilitate the highly efficient chemistry of metalloenzymes, and replicating these interactions in bioinspired coordination complexes are a longstanding goal of synthetic chemists.¹ In this presentation, we will describe our efforts towards synthesizing nonheme iron(II) complexes that feature novel tetradentate ligands with outer-sphere H-bond donors.²  These complexes are intended to mimic the structure and function of mononuclear nonheme iron enzymes that oxidize thiol-based substrates. While the mechanisms of these enzymes are not well understood^,, it is clear that H-bonding interactions play an important role in optimizing catalysis.^3,4 Inspired by this biological precedent, several ligands with mixed pyridyl and imidazolyl donors have been generated via efficient synthetic pathways that enable the incorporation of second-sphere phenylamine N-H donors.  The resulting Fe(II) complexes have been examined by single-crystal X-ray diffraction methods, which revealed that the ligands adopt the desired coordination geometry.  Moreover, strong H-bonding interactions between first-sphere ligands and outer-sphere N-H units are evident in the crystal structures.  Efforts to coordinate ligands that resemble the enzymatic substrates are ongoing, and reactivity studies with small molecules (O₂, NO) will be described.