Catalytic reduction of dinitrogen to ammonia using molybdenum porphyrin complexes

Hegg, Alexander S; Mercado, Brandon Q.; Miller, Alexander J. M.; Holland, Patrick L.

doi:10.1039/d2fd00166g

Cited by 5 publications

(3 citation statements)

References 96 publications

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“…83,84 Molybdenum-based materials and molecular complexes have been studied extensively due to its presence in nitrogenases. 85,86 Our very recent theoretical work on Mo + N 2 and Mo − + N 2 reactions disclosed that Mo can transfer five or six electrons to N 2 cleaving its bond and forming either N 2− Mo(V)N 3− or N 3− Mo(VI)N 3− . 11 However, the energy of NMoN is higher than that of the Mo(N 2 ) encounter complex (N 2 weakly interacting with Mo).…”

Section: Resultsmentioning

confidence: 99%

Potential of Molecular Catalysts with Electron-Rich Transition Metal Centers for Addressing Long-Standing Chemistry Enigmas

Androutsopoulos,

Sader,

Miliordos

2024

J. Phys. Chem. A

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Molecular complexes with electron-rich metal centers are highlighted as potential catalysts for the following five important chemical transformations: selective conversion of methane to methanol, capture and utilization of carbon dioxide, fixation of molecular nitrogen, water splitting, and recycling of perfluorochemicals. Our initial focus lies on negatively charged metal centers and ligands that can stabilize anionic metal atoms. Catalysts with electron-rich metal atoms (CERMAs) can sustain catalytic cycles with a “ping-pong” mechanism, where one or more electrons are transferred from the metal center to the substrate and back. The donated electrons can activate the chemical bonds of the substrate by populating its antibonding orbitals. At the last step of the catalytic cycle, the electrons return to the metal and the product interacts only weakly with the formed anion, which enables the solvent molecules to remove the product fast from the catalytic cycle and prevent subsequent unfavorable reactions. This process resembles electrocatalysis, but the metal serves as both an anode and a cathode (molecular electrocatalysis). We also analyze the usage of CERMAs as the base of Frustrated Lewis pairs proposing a new type of bimetallic catalysts. This Featured Article aspires to initiate systematic experimental and theoretical studies on CERMAs and their reactivity, the potential of which has probably been underestimated in the literature.

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Section: Resultsmentioning

confidence: 99%

Potential of Molecular Catalysts with Electron-Rich Transition Metal Centers for Addressing Long-Standing Chemistry Enigmas

Androutsopoulos,

Sader,

Miliordos

2024

J. Phys. Chem. A

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“…An added advantage is the reducing nature of the porphyrin ligand, which has been highlighted in the study by Hegg et al wherein the porphyrin ligands induce the reduction of N 2 to NH 3 . It is also important to note that the metal center in the metalloporphyrin MOFs also serves as a single-atom catalyst (SAC) as the four nitrogen atoms in the porphyrin network form a highly stable M–N 4 complex, thereby avoiding metal aggregation or migration. , The single-atom nature of the Fe center in metalloporphyrin MOFs has been affirmed from the work by Zhang et al when PCN-222(Fe) MOF comprised of (iron(III)meso-tetra(4-carboxyphenyl)porphyrin chloride) and H 2 -TCPP (tetra(4-carboxyphenyl)porphyrin) showed an excellent electrocatalytic NRR yield of 1.56 × 10 –11 mol cm –2 s –1 with a Faradaic efficiency (FE) of 4.51% at −0.05 V vs reversible hydrogen electrode (RHE).…”

Section: Introductionmentioning

confidence: 99%

Surface Electronic Properties-Driven Electrocatalytic Nitrogen Reduction on Metal-Conjugated Porphyrin 2D-MOFs

Maibam,

Orhan,

Krishnamurty

et al. 2024

ACS Appl. Mater. Interfaces

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Two-dimensional (2D) metal organic framework (MOF) or metalloporphyrin nanosheets with a stable metal-N 4 complex unit present the metal as a single-atom catalyst dispersed in the 2D porphyrin framework. First-principles calculations on the 3dtransition metals in M-TCPP are investigated in this study for their surface-dependent electronic properties including work function and dband center. Crystal orbital Hamiltonian population (-pCOHP) analysis highlights a higher contribution of the bonding state in the M−N bond and antibonding state in the N−N bond to be essential for N−N bond activation. A linear relationship between ΔG max and surface electronic properties, N−N bond strength, and Bader charge has been found to influence the rate-determining potential for nitrogen reduction reaction (NRR) in M-TCPP MOFs. 2D Ti-TCPP MOF, with a kinetic energy barrier of 1.43 eV in the final protonation step of enzymatic NRR, shows exclusive NRR selectivity over competing hydrogen reduction (HER) and nitrogenous compounds (NO and NO 2 ). Thus, Ti-TCPP MOF with an NRR limiting potential of −0.35 V in water solvent is proposed as an attractive candidate for electrocatalytic NRR.

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“…[5] Among the transition metal complexes, molybdenum complexes have been revealed to work as effective catalysts for ammonia formation under ambient reaction conditions. [5d, [6][7][8] In 2019, we found that the ammonia formation proceeded quite rapidly from the reaction of dinitrogen with samarium diiodide (SmI 2 ) as a reductant and water (H 2 O) as a proton source in the presence of a catalytic amount of a molybdenum(III) trichloride complex bearing pyridine-based PNP-type pincer ligand ([MoCl 3 (PNP)]: 1 a) (Scheme 1a). The proposed reaction pathway of the catalytic ammonia formation using 1 a as a catalyst is shown in Scheme 1b.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Activity of Molybdenum Complexes Bearing PNP‐Type Pincer Ligand toward Ammonia Formation

et al. 2023

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We newly designed and prepared a novel molybdenum complex bearing a 4‐[3,5‐bis(trifluoromethyl)phenyl]pyridine‐based PNP‐type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum‐imide complexes bearing various substituted pyridine‐based PNP‐type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification.

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Catalytic reduction of dinitrogen to ammonia using molybdenum porphyrin complexes

Abstract: Porphyrin complexes are well-known in O2 and CO2 reduction, but their application to N2 reduction has not yet been reported. Here, we show that oxo and nitrido complexes of molybdenum...

Cited by 5 publications

References 96 publications

Potential of Molecular Catalysts with Electron-Rich Transition Metal Centers for Addressing Long-Standing Chemistry Enigmas

Potential of Molecular Catalysts with Electron-Rich Transition Metal Centers for Addressing Long-Standing Chemistry Enigmas

Surface Electronic Properties-Driven Electrocatalytic Nitrogen Reduction on Metal-Conjugated Porphyrin 2D-MOFs

Catalytic Activity of Molybdenum Complexes Bearing PNP‐Type Pincer Ligand toward Ammonia Formation

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