Hydrogenase Enzymes and Their Synthetic Models: The Role of Metal Hydrides

ABSTRACTFirst principles calculations based on gradient corrected density functional theory are carried out to understand the electronic structure and mechanisms responsible for desorption of hydrogen from Ti doped and vacancy containing sodium-alanate (NaAlH4). The energy necessary to remove a hydrogen atom from Ti doped NaAlH4 is significantly smaller than that from pristine NaAlH4 irrespective of whether Ti substitutes the Na or the Al site. However, the presence of Na and Al vacancies is shown to play an even more important role: The removal of hydrogen associated with both Na and Al vacancies is found to be exothermic. It is suggested that this role of vacancies can be exploited in the design and synthesis of complex light metal hydrides suitable for hydrogen storage.

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Positron binding to alkali-metal hydrides: The role of molecular vibrations

Physical Review A ◽

10.1103/physreva.73.022705 ◽

2006 ◽

Vol 73 (2) ◽

Cited By ~ 46

Author(s):

Franco A. Gianturco ◽

Jan Franz ◽

Robert J. Buenker ◽

Heinz-Peter Liebermann ◽

Lukáš Pichl ◽

...

Keyword(s):

Alkali Metal ◽

Metal Hydrides ◽

Molecular Vibrations

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Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts

Chemical Science ◽

10.1039/c6sc00767h ◽

2016 ◽

Vol 7 (7) ◽

pp. 4036-4043 ◽

Cited By ~ 85

Author(s):

Masaaki Kitano ◽

Yasunori Inoue ◽

Hiroki Ishikawa ◽

Kyosuke Yamagata ◽

Takuya Nakao ◽

...

Keyword(s):

Low Temperature ◽

Essential Role ◽

Ammonia Synthesis ◽

Metal Hydrides ◽

Low Pressure ◽

Hydride Ion ◽

Synthesis Catalysts

Ruthenium-loaded metal hydrides with hydrogen vacancies function as efficient catalysts for ammonia synthesis under low temperature and low pressure conditions.

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Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2109241118 ◽

2021 ◽

Vol 118 (49) ◽

pp. e2109241118

Author(s):

Linh N. V. Le ◽

Gwendolyn A. Bailey ◽

Anna G. Scott ◽

Theodor Agapie

Keyword(s):

Active Sites ◽

Chemical Properties ◽

Metal Centers ◽

Bridging Ligand ◽

Reduction Potentials ◽

Protein Active Sites ◽

Physical And Chemical ◽

Synthetic Models ◽

And Chemical Properties

Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an Fe-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMco displays eight metal centers bridged by sulfides and a carbide having the MFe7S8C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing how the carbon bridge affects the physical and chemical properties of the cluster, we isolated synthetic models of subsite MFe3S3C displaying sulfides and a chelating carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*M’Fe3S3X]n−, where M’ = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = Tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M’ results in minor changes, the chelating, μ3-bridging carbyne has a large impact on reduction potentials, being up to 1 V more reducing compared to nonchelating N and S analogs.

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Numerical study of the Martelange mine to be used as underground reservoir for constructing an Underground Pumped Storage Hydropower plant

Advances in Geosciences ◽

10.5194/adgeo-45-51-2018 ◽

2018 ◽

Vol 45 ◽

pp. 51-56 ◽

Cited By ~ 1

Author(s):

Estanislao Pujades ◽

Philippe Orban ◽

Pierre Archambeau ◽

Sebastien Erpicum ◽

Alain Dassargues

Keyword(s):

Numerical Study ◽

Surrounding Medium ◽

High Capacity ◽

Abandoned Mines ◽

Hydropower Plant ◽

Underground Reservoir ◽

Pumped Storage ◽

Surface Reservoir ◽

Synthetic Models

Abstract. Underground Pumped Storage Hydropower (UPSH) using abandoned mines has been considered as a potential high capacity Energy Storage Systems. In UPSH plants, the excess of electricity is stored in the form of potential energy by pumping water from an underground reservoir (abandoned mine in this paper) to a surface reservoir, while electricity is produced (when the demand increases) discharging water from the surface into the underground reservoir. The main concerns may arise from the water exchanges occurring between the underground reservoir and the surrounding medium, which are relevant in terms of environmental impact and UPSH efficiency. Although the role of the water exchanges has been previously addressed, most studies are based on synthetic models. This work focuses on a real abandoned slate mine located in Martelange (Belgium). The effects of different rehabilitation works to prepare the mine as an underground reservoir are assessed in terms of groundwater exchanges and their associated consequences.

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Surgical Simulation: The Way Forward or a Waste of Time?

Bulletin of The Royal College of Surgeons of England ◽

10.1308/147363513x13690603818020 ◽

2013 ◽

Vol 95 (9) ◽

pp. 288-288

Author(s):

Mary Murphy

Keyword(s):

Surgical Procedures ◽

Surgical Simulation ◽

Junior Doctors ◽

Training Methods ◽

Work Time ◽

Training Models ◽

The Public ◽

Synthetic Models ◽

Official Recognition

Traditional surgeons, trained in the old-fashioned apprenticeship system, are often bemused by new training models, and the role of modern training methods such as surgical simulation. Regulation of work time for junior doctors and expectations of the public have led to an increasing role for simulation. Now there is even official recognition of 'simulated cases' in trainees' logbooks and as part of their work-based assessments. So, is this revolution for better or for worse? Traditionally surgeons have always advocated dissection, simulation and courses using cadavers. How does operating on cadavers and synthetic models compare? Cadavers can be useful for teaching and appreciating anatomy but how useful are they for simulation of surgical procedures and operations?

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Cluster Models of FeMoco with Sulfide and Carbyne Ligands: Effect of Interstitial Atom in Nitrogenase Active Site

10.26434/chemrxiv.14614152.v1 ◽

2021 ◽

Author(s):

Linh Le ◽

Gwendolyn Bailey ◽

Anna Scott ◽

Theodor Agapie

Keyword(s):

Active Sites ◽

Interstitial Atom ◽

Metal Centers ◽

Bridging Ligand ◽

Reduction Potentials ◽

Formal Charge ◽

Protein Active Sites ◽

Cluster Composition ◽

Synthetic Models

Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an iron-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMoco displays eight metal centers bridged by sulfides and a carbide having the MoFe7S8C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing its function, we isolated synthetic models of subsite MFe3S3C displaying sulfides and a carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*MFe3S3X]n-, where M = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M results in minor changes, the μ3-bridging ligand X has a large impact on reduction potentials, with differences higher than 1 V, even for the same formal charge, the most reducing clusters being supported by the carbyne ligand.

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