Heterolytic H₂ Activation Mediated by Low-Coordinate L₃Fe-(μ-N)-FeL₃ Complexes to Generate Fe(μ-NH)(μ-H)Fe Species

The diiron μ-nitride complexes, {L₃Fe^II(μ-N)Fe^IIL₃}^- and L₃Fe^III(μ-N)Fe^IIL₃, heterolytically activate hydrogen (1 atm) at ambient temperature in solution (L₃ = [PhB(CH₂PPh₂)₃]^-). These transformations lead to structurally unique {L₃Fe^II(μ-NH)(μ-H)Fe^IIL₃}^- and L₃Fe^III(μ-NH)(μ-H)Fe^IIL₃ products. X-ray data establish a marked reduction in the Fe−Fe distance upon H₂ uptake, and spectroscopic data establish both Fe^IIFe^II species to be diamagnetic, whereas the Fe^IIIFe^II species, L₃Fe^III(μ-N)Fe^IIL₃ and L₃Fe^III(μ-NH)(μ-H)Fe^IIL₃, populate doublet ground states with thermally accessible higher spin states.