An Iron(III) Dithiolene Complex as a Functional Model of Iron Hydrogenase

The synthesis of renewable fuels from abundant water or the greenhouse gas CO 2 is a major step toward creating sustainable and scalable energy storage technologies. In the last few decades, much attention has focused on the development of nonprecious metal-based catalysts and, in more recent years, their integration in solid-state support materials and devices that operate in water. This review surveys the literature on 3d metal-based molecular catalysts and focuses on their immobilization on heterogeneous solid-state supports for electro-, photo-, and photoelectrocatalytic synthesis of fuels in aqueous media. The first sections highlight benchmark homogeneous systems using proton and CO 2 reducing 3d transition metal catalysts as well as commonly employed methods for catalyst immobilization, including a discussion of supporting materials and anchoring groups. The subsequent sections elaborate on productive associations between molecular catalysts and a wide range of substrates based on carbon, quantum dots, metal oxide surfaces, and semiconductors. The molecule–material hybrid systems are organized as “dark” cathodes, colloidal photocatalysts, and photocathodes, and their figures of merit are discussed alongside system stability and catalyst integrity. The final section extends the scope of this review to prospects and challenges in targeting catalysis beyond “classical” H 2 evolution and CO 2 reduction to C 1 products, by summarizing cases for higher-value products from N 2 reduction, C x >1 products from CO 2 utilization, and other reductive organic transformations.

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“…113 Maleonitrile dithiolate-coordinated complex Fe3 provides an additional example where the S-atoms are thought to act as proton shuttles. 145…”

Section: Homogeneous Catalysismentioning

confidence: 99%

Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes

et al. 2019

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“…Kaur–Ghumaan et al15 showed that a mononuclear iron(II) complex is able to evolve molecular hydrogen through two proton reduction steps. A recently reported pentacoordinate iron(III) dithiolene complex catalyzes H 2 evolution at a mild overpotential of 0.3 V vs. Ag/AgCl 8. This [Fe III (mnt) 2 (SPh)] 2– complex ( 1 , mnt = maleonitrile dithiolate; Figure 1B) has a distorted square‐pyramidal geometry.…”

Section: Introductionmentioning

confidence: 96%

“… Schematic representation of (A) the [FeFe]‐hydrogenase active site and (B) complex 1 , a pentacoordinate Fe III functional mimic of hydrogenase 8…”

Section: Introductionmentioning

confidence: 99%

“…As only the distal Fe d atom is the site of proton binding and reduction, mononuclear iron complexes have been designed and investigated as functional models for [FeFe]‐hydrogenase 14. Mononuclear complexes containing iron(II)15,16 and iron(III)8 have recently been synthesized and functionally studied. Kaur–Ghumaan et al15 showed that a mononuclear iron(II) complex is able to evolve molecular hydrogen through two proton reduction steps.…”

Section: Introductionmentioning

confidence: 99%

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Spin‐State‐Dependent Properties of an Iron(III) Hydrogenase Mimic

Edler

Stein

2014

Eur J Inorg Chem

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A biomimetic mononuclear iron(III) model complex was investigated in detail by density functional theory (DFT) calculations. Structural and energetic criteria were employed to confirm the S = 3/2 intermediate state to be the ground state. The ground state was verified by using both pure and hybrid functionals with different amounts of exact Hartree-Fock exchange. A comprehensive study of the influence of the functional as well as thermodynamic corrections to the energetic ordering of spin states was performed. A modified B3LYP functional with 10 % Hartree-Fock exchange was able to reproduce the structural properties in excellent agreement

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“…Later, the dianionic iron maleonitrile dithiolate complex 13b was presented and its structure was crystallographically determined. 138 The thiophenol moiety completes the coordination sphere of the Fe(III) center and the complex takes a distorted square pyramidal geometry, where a thiophenol benzene hydrogen atom interacts with two ligating sulphur atoms. Complex 13b catalyses proton reduction at a relatively low reduction potential of −0.309 V vs. Ag/AgCl (−0.67 V vs. Fc + /Fc) in acetonitrile and at −0.53 V vs. Ag/AgCl in water with TsOH as a source of protons.…”

Section: Reviewmentioning

confidence: 99%