A Functional [NiFe]Hydrogenase Mimic That Catalyzes Electron and Hydride Transfer from H ₂

Abstract

Chemists have long sought to mimic enzymatic hydrogen activation with structurally simpler compounds. Here, we report a functional [NiFe]-based model of [NiFe]hydrogenase enzymes. This complex heterolytically activates hydrogen to form a hydride complex that is capable of reducing substrates by either hydride ion or electron transfer. Structural investigations were performed by a range of techniques, including x-ray diffraction and neutron scattering, resulting in crystal structures and the finding that the hydrido ligand is predominantly associated with the Fe center. The ligand's hydridic character is manifested in its reactivity with strong acid to liberate H(2).

H2 and O2 activation by [NiFe]hydrogenases – Insights from model complexes

“…In that structure, as was hypothesized by past enzyme and model studies [1,7,[10][11][12][13], where Ni-SIa is defined as '0' [7]. For example, the hydride species, Ni-R, is placed at the 14.…”

“…The literature includes reports of numerous [NiFe]H 2 ase model complexes, but heterolytic cleavage of H 2 molecules using the NiFe complexes was only accomplished in 2013 [11,12]. Since the acetonitrile (CH 3 CN) ligand in the Ni-SIa model shown in Fig.…”

“…[NiFe]H 2 ase models [11,15]. Based on Requirements 1 and 2 for activation of H 2 and O 2 , we used triethyl phosphate and pentamethylcyclopentadienyl as the induction ligands to capture the hydrogen and oxygen molecules.…”

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex II: Neutron Scattering Instruments

“…In both maps, positive neutron scattering-length density was observed between the Ni and Fe atoms. Although the final R value (0.2581 for 931 I > 2σ(I) reflections) was higher than that in typical single-crystal neutron structure analysis of a metal complex because of the quality of the sample crystal, these Fourier maps strongly suggested that the [NiFe] model complex has the expected Ni(μ-D)Fe structure [148]. iBIX was originally designed for structure analyses of bio-macromolecules, and its sample environment was optimized for fragile and air-sensitive protein crystals.…”

Use of EPR Spectroscopy to Unravel Reaction Mechanisms in (Catalytic) Bond Activation Reactions: Some Selected Examples

“…Even though some of these systems might actually be amenable to studies with EPR spectroscopy, very little information is available in that direction [35][36][37]. The catalytic conversion of H 2 to protons and electrons has remained a challenging task with such structural mimics [39][40][41][42][43]. A second approach that takes functional inspiration from hydrogenases has also been successful in this regard [43][44][45][46].…”